Ok, been a while, but I think I've put together a custom power that works nicely, but first I'm going to cover the reasons I think a new power is justified.
1) I don't like the idea of locking down Physical Immunity. Since, unlike Immortals, they don't have a weakness to their death immunity, I don't see any harm in an Undying character taking a Physical Immunity of whatever type would normally be allowed by the group.
2) Wording it as a catch gets confusing since you have to describe the exceptions to the power instead of as its effects. In other words, "You are immune to death" is easier to understand then "Physical Immunity doesn't apply to anything except death", at least when it is more complex then those simple examples.
3) There are other particulars I think fit well with the template and they need their own power any way, so it don't hurt to move the no-death effect to that power.
Anyway, that said, here is the power I came up with.
Deathless [-2]Note: The result of extreme measures that could cause total destruction of the character (for example, immersion in a star) should be decided during character creation if they are applicable to the story.
Effects:Endless Life: Drowning, starvation, gun-shots, stabbing, explosions, fire, etc, the cause doesn't matter, you are so full of life-force that death can not touch you; however, if your brain is in a shape to process input, you'll get to feel every agonizing moment of it. You take stress and consequences normally, though no "death" result is ever possible. This essence of life resides in a specific organ of the body (generally head or heart) decided on at creation time. Without any upgrades to this ability, the character can only control pieces of their body when they are connected to this organ. For example, if the life-essence was centered in the head and the head was removed, the eyes and mouth would still be controllable, but the body would not.
Parts of a Whole [-2]: Increasing the refresh cost of this ability by 2 will allow severed body parts to be controlled independently, hands can still grab, eyes can still see, legs can still kick, etc. All actions performed by the body parts not connected to the specified essence center receive a -1 penalty if they are visible to the character and at least -2 if not. If a new body part is regenerated to replace the old one, then all connection to the previous part is lost.
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My question, does the upgrade cost of -2 sound right?
I also have a third effect I'm working on, but I can't figure out what type of benefit it should get. This is what I have so far.
The thematics...
Pain Don't Hurt: Living through death a handfull of times really puts pain into perspective.
Here is what I've been thinking about for the rest...
a) Gain +3 on any roll to resist or overcome physical pain.
or
b) Receive 2 additional Mild (umm.. Mental or Physical?) Consequence.
or
c) You get 2 additional (again.. Mental or Physical?) Stress boxes.
As you can see, I'm not sure if the "resistance to pain" should model around Mental or Physical. As for the numbers in any of those, they were just of the top of my head.
Any advice on the mechanics of how to implement "getting use to the pain after living though damage that would kill everyone else"?