Good attitude.
I think the first step towards cleaning this up is to decide what exactly it should work against. If I wear magical armour that sends attacks to the Nevernever, should it work against this?
The second step is probably deciding whether this effect should remain absolute. There's a certain appeal to making this work as well against a 30-shift ward as against a 5-shift shield, but it's kinda hard to balance that. So for the sake of convenience it might be worth making it less absolute.
Then it should be made clear whether this destroys blocks or simply bypasses them.
Once all that's done, the Power should be a lot easier to work with.
On an unrelated note, here are the possession-related Powers I wrote a while back. Comments welcome, of course.
INHABIT [-2]
Description: You can enter inanimate objects, which you can then use as though they were physical bodies.
Musts: You must have an Aspect referring to the objects you inhabit, which can be invoked or compelled to reflect the abilities and limitations of your object-bodies.
Skills Affected: Many.
Effects:
Inhabitation. Once per scene, you may enter and control an inanimate object. While you are inside an object, you may control it as though it were your body. If your object-body is Taken Out, you may be ejected during Take-Out narration. Otherwise you may stay as long as you wish. Use your own skills and Powers to represent the abilities of your object-body. Spirit Form is an exception to this; if you have it, it's suppressed while you inhabit an object. If your object-body should logically have a Size Power that you don't have, you can't inhabit it. If it should logically lack a Size Power that you have, you lose your Size Power while inhabiting it. If you have a Size Power that is effectively a greater version of the one you need, you may reduce it; for example, a character with Titanic Size could inhabit an object with Hulking Size.
Semi-Animate. While inhabiting an object, you have the Semi-Animate Power.
Abandoned Body. While you are inside an object, you can act only through that object. If you have a physical body, it lies vulnerable until you leave the object. If you have the Spirit Form Power, you are entirely subsumed into the object until you leave into the area surrounding the object.
Inhabit Specific Type Of Thing [+1]. You can only inhabit a specific type of object, like cars or corpses or clouds. The type of object should be specific enough that one won't always be available to inhabit.
Improved Inhabitation [-varies]. For every point of Refresh invested in this upgrade, you can copy one Refresh worth of Powers or one Stunt from an object whenever you inhabit that object. Select the Powers that you copy when entering the object. Inhabiting the corpse of a swordsman might grant a sword-related stunt, while inhabiting an iron statue might grant Toughness. This may be used to purchase Size Powers, allowing you to possess objects that would normally be too big or too small for you.
SPIRITUAL PARASITE [-1]
Description: You can invade the minds of others. You can't take over completely, but you can influence your hosts pretty strongly.
Skills Affected: Discipline, others.
Effects:
Spiritual Parasitism. You may attempt to enter the bodies of other characters, willing or otherwise. Entering an unwilling character requires you to win a mental conflict, which uses the same timeframe and initiative as a physical fight. Discipline is used to attack and defend in that conflict. During the conflict, you are treated as though you were inside your target's body for the purposes of the Abandoned Body and You're Not Hurting Me Trappings. Taking an action in that conflict takes a character's full attention. If you win the conflict, you may enter the target's body. If you lose, then you fail to do so and may not try again until the next session.
Sponsor. While you are inside a character, that character has a temporary Aspect that indicates your presence. In addition, you may allow them to spend your Fate Points. For each Fate Point they spend this way, they acquire a point of sponsor debt. The debt is to you, and you may choose to use it for a Compel whenever you please.
Corrupting Influence. While you are inside another character, both you and your host gain a new stress track called the control track. The control track's length is determined by Conviction, and stress and consequences inflicted to it do not heal normally. At the end of each scene, you and your host may make a control attack against each other. Use Discipline to attack and to defend. If your host takes you out, you must leave their body. If you take them out, clear both your control track and theirs. Also you may either inflict a Compel upon them as though they had taken a point of sponsor debt to you or change one of their permanent Aspects. The extent of an Aspect change caused by this Power is roughly equal to the extent of an extreme consequence.
You're Not Hurting Me. You cannot be targeted with physical or mental attacks while in another character's body, barring special Powers or unusual circumstances. Social attacks can target you normally, though, and you may not transfer backlash or stress costs to your host. If your host is drawn into a mental conflict, you may participate in that conflict. If you leave behind your physical body in order to use this Power, attacks against it bypass this effect.
Abandoned Body. While you are in another character's body, you cannot take physical actions. Nobody save your host can perceive you unless they have The Sight or another such effect. If you have a physical body, it lies vulnerable until you leave your host. If you have the Spirit Form Power, you are entirely subsumed into your host until you leave into the area surrounding your host's body.
Helpful Spiritual Parasite [-1]. While you are in another character's body, you may attempt grant that character a +1 bonus whenever they use any skill. If they accept the bonus, you get a stackable +2 bonus to the control attack that you make at the end of that scene.
Benevolent Spiritual Parasite [+1]. (Requires Helpful Spiritual Parasite) You may not make a control attack at the end of a scene unless your host accepted a bonus that scene. And even if they did accept a bonus, your attack skill is automatically Mediocre (+0) before bonuses. Whenever your host goes a full session without using a bonus, they may clear their control stress track and begin to recover control consequences normally. On the upside, your host can no longer make control attacks against you at the end of each scene. Barring some sort of exorcism, you're there until you decide to leave.
SPIRITUAL CO-PILOT [-1]
Description: A spirit dwells inside you, granting you power in exchange for control over you. Draw upon it too heavily, and you may become its puppet.
Musts: You must have an Aspect reflecting your spiritual partner. If you act against your Co-Pilot's agenda, a Compel may deny you access to this Power.
Note: This Power is usually taken alongside the Sponsor Power. It is not compatible with Immunity to the stress that it inflicts.
Skills Affected: Discipline, others.
Effects:
Spiritual Power. Whenever you use a skill, you may choose to treat it as though it were one point higher. Do this before rolling.
The Struggle For Control. You have an additional stress track, called the control track. The length of this track is determined by your Conviction. Stress and consequences taken on this track do not begin to heal until you go a full session without using Spiritual Power.
The Price Of Power. At the end of any scene in which you use the Spiritual Power trapping, you suffer a control attack. The accuracy of this control attack is twice the number of times you used Spiritual Power in that scene, and has no weapon rating. Defend with your Discipline skill. If this attack takes you out, you receive a Compel as though you had taken a point of Sponsor Debt. Alternately, the GM may choose to alter one of your permanent Aspects.
ENTHRALLMENT [-2]
Description: You can control minds. It's not quick or easy, but it's effective.
Skills Affected: Discipline.
Effects:
Domination. You may engage a willing or helpless target in a mental conflict. Discipline is used to attack and to defend. You automatically win initiative, and taking an action in this conflict requires a character's full attention. If you are taken out, the conflict ends and you may not resume it for twenty four hours. Each exchange in this conflict takes roughly half an hour by default. You can rush this, but you'll suffer a penalty to all rolls in the rushed exchange. This penalty is -1 for a five minute exchange, -2 for a one minute one, and -3 for a combat-time exchange.
Enthrallment. If you take your target out, you may turn them into a rough thrall or into a Renfield. A rough thrall is identical to the character it once was, except that it now obeys you robotically and takes no initiative. Change its High Concept to reflect that. A rough thrall can recover given roughly a month without re-enthrallment, the help of a wizard or therapist, or a Compel against you on one of its aspects triggered by an attempt to force it to do something diametrically opposed to its nature. A Renfield is similar to a rough thrall, but retains none of its previous memories or identity. Renfields are incurable.
Superior Enthrallment [-1]. Your Enthrallment attacks inflict two additional stress. In addition, you may transform defeated targets into fine thralls. A fine thrall is identical to the character it once was, except it now seeks the goals you assign for it in place of its own. Change its High Concept to reflect that. You may also transform thralls into supernatural beings. Select four Refresh of Powers and stunts. Whenever you enthrall a character, you may grant them those abilities. Change their Aspects to reflect their new nature, as normal.
SPIRITUAL SYMBIOTE [-1]
Description: You're a spiritual symbiote of sorts; you enter the bodies of other people and make them stronger.
Musts: You must have an Aspect reflecting this Power.
Skills Affected: Many.
Effects:
Integration. You may enter the bodies of willing characters. Entering or leaving a body in a conflict takes your action, and you can stay until you decide to leave or are kicked out by your host. While you are in a character's body, that character has access to your stunts, skills, and Powers. Size Powers and Spirit Form are exceptions to this. Other exceptions should be handled through Compels or through the Limitation Power.
Abandoned Body. While you are in another character's body, the only things you can do are look through your host's senses and talk to your host. Nobody save your host can perceive you unless they have The Sight or another such effect. If you have a physical body, it lies vulnerable until you leave your host. If you have the Spirit Form Power, you are entirely subsumed into your host until you leave into the area surrounding your host's body.
You're Not Hurting Me. You cannot be targeted with physical attacks while in another character's body, barring special Powers or unusual circumstances. Characters looking to take you down violently will probably have to settle for knocking the person whose body you're using unconscious. Mental and social attacks can target you normally, though, and you may not transfer backlash or physical stress costs to your host. If your host is drawn into a mental conflict, you may participate in that conflict. If you leave behind your physical body in order to use this Power, attacks against it bypass this effect.
POSSESSION [-1]
Description: You can take over the bodies of others. Maybe only if they consent, maybe even if they don't.
Skills Affected: Discipline, others.
Effects:
Possession. You may enter the bodies of willing characters. Entering or leaving a body in a conflict takes your action, and you can stay until you decide to leave or are kicked out by your host. While you are in a character's body, you may control that body as though it were your own. Use your own skills and Powers when doing so. Size Powers and Spirit Form are an exception to this: use your host's Size Powers in place of your own, and if you have Spirit Form it is suppressed while you're in someone else's body. You may also use certain other Stunts and Powers possessed by your host, generally those relating to raw physical ability or the reactions of other characters to your host's body. Some of the host's skills may also modify your own, generally along the same guidelines as Powers and Stunts. The GM is the final judge of which of the host's Powers and Skills and Stunts apply to you.
You're Not Hurting Me. You cannot be targeted with physical attacks while in another character's body, barring special Powers or unusual circumstances. Characters looking to take you down violently will probably have to settle for knocking the person whose body you're using unconscious. Mental and social attacks can target you normally, though, and you may not transfer backlash or physical stress costs to your host. If your host is drawn into a mental conflict, you may participate in that conflict. If you leave behind your physical body in order to use this Power, attacks against it bypass this effect.
Spiritual Eviction. If you end up controlling a host who wants you out, that host may engage you in an opposed Discipline roll. If they win, you are forced out of their body. If you entered their body with their consent, your host may attempt one such roll as soon as they decide to kick you out. Regardless, they may attempt one such roll every time you control their body for another continuous day and every time you use their body to damage them or something they care about. In extreme situations, such as forced suicide, your host may benefit from a circumstantial bonus to the opposed Discipline roll.
Abandoned Body. While you are in another character's body, you can act only through that body. Nobody save your host can perceive you unless they have The Sight or another such effect. If you have a physical body, it lies vulnerable until you leave your host. If you have the Spirit Form Power, you are entirely subsumed into your host until you leave into the area surrounding your host's body.
Hostile Possession [-2]. You may attempt to possess unwilling victims. This requires you to win a mental conflict, which uses the same timeframe and initiative as a physical fight. Discipline is used to attack and defend in that conflict. During the conflict, you are treated as though you were inside your target's body for the purposes of the Abandoned Body and You're Not Hurting Me Trappings. Taking an action in that conflict takes a character's full attention. If you lose the conflict, you fail to possess the target and can't try again until the next session. If you win, you possess the target normally. If a character is possessed by multiple characters with this Power, the most recent possession takes precedence.
SPIRIT FORM [-3]
Description: You are an incorporeal spirit form, able to pass through walls and other barriers in the mortal world. Thresholds still have an almost physical reality to you, however.
Skills Affected: Many, especially Conviction.
Note: This power may not normally be attached to Human Form, Feeding Dependency, an Item Of Power, Magical Self-Enhancement, or any other power that can "turn off" the powers it is attached to. The Astral Projection and Manifestation upgrades, if taken, entirely remove this restriction except with regards to Human Form.
Effects:
Insubstantial. You are invisible, inaudible, and incorporeal. This means that you can neither affect nor be affected by physical things, except as dictated under Vulnerabilities. Any magic that you cast is also incorporeal, and useless against anything physical. However, you can perceive the physical world normally, and under some circumstances it may be possible for physical characters to perceive and communicate with you. Characters with this power may affect each other freely.
Shaped By Belief. Your very existence is defined by belief. As a result, you are not closely bound by physical reality. You do not need to eat or sleep or breathe. Furthermore, you do not excrete wastes and you do not age. You are immune to both poison and disease. You may make Maneuvers and Declarations with Conviction to define your physical form and the nature of your interactions with the world.
No Real Body. You don't have a real body. Powers that allow characters to enter the bodies of others, like Possession, cannot be used on you.
Vulnerabilities. Certain physical things can harm you despite your intangibility. These things include ghost dust and fire. What's more, you cannot cross thresholds at all.
Unrealistic Spirit Form [-1]. The laws of physics only affect you if you think they should. Teleportation is possible for you. You may substitute your Conviction skill for your Might skill when exerting force, your Athletics skill when moving, or for any other physical skill as the GM feels is appropriate.
Spiritual Body [-0]. Your body and your mind are the same thing. You have one stress track that is used for both mental and physical stress. Its length is determined by your Conviction skill. Size, Toughness, and Stoicism powers apply to this track, but mental stress bypasses physical Powers and vice versa. Consequences taken on this track do not recover naturally unless you provide some form of special justification, generally involving the absorption of memories. More severe consequences require more elaborate justifications.
Quasi-Solid Spirit Form [-1]. You can exert a tiny amount of force on the material world. Normally this does nothing of importance, but when machinery is around you can often interfere with it. You may use Conviction to make maneuvers disrupting physical machinery and moving small objects.
Optional Spirit Form [-2]. You may suppress or reactivate this Power whenever you please. Doing so takes an action if you are engaged in a conflict. Using this trapping is an insane act for a ghost, and as such this trapping may not be possessed by sane ghosts. (Other forms of spirit might not have this limitation, and physical creatures that can become ethereal almost certainly don't.)
Projected Spirit Form [-1]. You are a physical creature, but you can leave your body when you feel inclined. You normally do not have access to this power, but you may gain access to it any time by taking a supplemental action. When you do so, your physical body is unconscious and immobile. You may return to your physical body at any time by physically entering it with a supplemental action. This upgrade is not compatible with Optional Spirit Form.
Involuntary Spirit Form [+1]. (Requires Optional Spirit Form or Projected Spirit Form) You have no control over whether or not you are corporeal at any given time. Choose a condition in collaboration with the GM. This condition determines whether or not this power is active at any given time.