In a low power game, my glamour based character may end up being the 'tank'.  He has a shadow form that is very tough, and his illusions can steadily pile useful aspects, so he can't be ignored, but he doesn't have much direct striking power.

You could have someone with a very high evocation block be the tank.  Or someone with high toughness, or high athletics + speed and stunts to make their dodge even higher.  Regardless, they also need to have something that causes the enemy to focus exclusively on them, instead of on squishier targets.

If you had beast change in a Modular pool, can you have Different beast changes?

So could you have a tracker hound form, that has high survival and alertness, and a tracking sense, as well as an animal form he fights in with high athletics and fists?

Some feet in the water concepts:

You can have a one trick pony wizard.
-3 for Evocation +1 power for main element
-1 for refinement +2 power for main element, +1 control

magic item, +2 power for one spell, +2 control for one spell, or 8 power, 7 control for one spell.

Even a more generalist wizards could have 5 power rotes in their main specialty.

A specialist in ritual could easily get enough control so they could reliably pour 1 or 2 power an exchange with no chance of failure.  A specialist in conjuration could do a ritual that "would create enough faux frogs to overrun a city park" for 11 complexity, and that would be easy for them.

Or a basic supernatural thug
super natural strength, speed, toughness and recovery, with a -3 catch for the last two.  Even one level of toughness means 3 more shifts will be required before you have to take a consequence.

You could have a wizard who evokes darkness and has cloak of darkness, and a stunt to give Conviction the stealth trapping.

At 6 refresh, bad ass normals can be quite effective.  A couple of refresh to make their gun or martial arts more effective, and more fate points to spend on things like Killer Blow, and a specialized normal will be very effective within their specialization.

You can make a shapeshifter with Beast change which has access to very different skills.

You could have someone with Psychometry, "Gives lore the investigation trapping", the use Lore for defense power "see 3 seconds into the future" and super speed, and you have the basis for someone with a rather strange relationship with Time.

You could have a Faith based character with Righteousness, Holy Touch, and a custom stunt that allows you to apply that Holy Touch to your weapons, and have a refresh left over to be extra good with either weapons or guns.

There was a cool moment in the Pink Floyd movie, The Wall, where the bombers broke free and bombed the Germans in the Bulge.  The moment of the cavalry coming, like Gandalf riding with the Rohan, is pretty powerful.

The first flower, or the first signs of spring could capture the smell of hope.

There is always the magically inquisitive pixie who investigates the potion carrying characters backpack.

He doesn't do anything harmful.  He doesn't activate any of them.  And he carefully puts the labels back on, and he is Quite sure he put the labels on the same potion bottles they were on originally.

Might want to just do a Lore check before using that potion, just to be sure.

One thing to consider with all these powerful wards, they are likely tied to being renewed at particular times.

So if you have a ward that lasts a month, that means you are probably tied up on the new moon each month, renewing it.  I suppose you could have a spell that lasts 2 (units) that you renew each (unit), so you have SOME flexibility.

For the uber forts, consider a flying, invisible fortress.  If you can't be in the same general area of the target ward to cast your ritual, you can't summon the power to break its wards.

Or put your fort inside a volcano.  Basically, create the warded area, then do major earth magic to activate the volcano.  Someone attacking the place will have to nullify the volcano first to even get close to the wards.  This buys some amount of time, and you can disrupt the spells they use to protect themselves from the volcano.

For people who use magic to break barriers routinely, there is always the AD&D trap:  Dispel magic removes the barrier holding something nasty back.  Or a hex causes a magnetic seal to break, releasing scorpions, fuel air bomb, werewolves etc...

Also, consider the escape route.  You want your enemies forced to enter only one way, but you want to be able to get out.  And you will want to be able to get out faster than your enemies can pursue.  So have a fancy and fast escape, either magical or technological.  If pursued by mundane foes, retreat the magical route, they won't be able to follow.  If pursued by mortal wizards, the technological route simply won't work after they blow through the doors.

If pursued by non-mortal wizards, you need a route through a powerful threshold or other barrier.  So you have an escape route under the Vatican, the Wailing Wall, the Rock of Mecca, or perhaps Ayres Rock.

A wall alone simply does not make a fort.  You can slow people down, but it has to have active defenders unless the defenses are just to stop a surprise attack, to allow the inhabitant to flee to another bolthole.  Making a fort with only one entrance makes it hard for the defenders as well, as it is also hard for them to get out.

You could have a fort defended by phantoms, copies of the defenders which soak up attacks that would otherwise hurt the defenders.  You could have areas with Aspects that could be tapped by defenders who are attuned to the stored energies of the fortress.  You can have divination and communication within the structure prepared.

But absolute fortress walls that don't require attention?  That is Maginot Wall thinking.  I would imagine that there were periods in the history of wizards where defensive magic lore outstripped the lore of breaking such barriers down, or were beyond the available resources most of the time, and so independent wizards or groups of wizards had a greater ability to thumb their nose at the White Council with impugnity... for minor issues, anyway.

Possibly a little hinky, but is the "Office of the Presidency" something you would handle as an Item of Power.

"It is what it is.  +2 to resources roll Provided it is in line with the OotP, once per scene"

I had been thinking of some background for a wizard who had been involved in shutting down the CIA's mindreading and other psychic phenomena program in the 1960s.  I am trying to come up with a good aspect relating to his training, that he basically trained against what he expected to face.  So he and a couple other apprentices were trained on how to resist mind probes and domination, and to do that, they also had to learn how to do mind probes and domination type mental attacks.

Basicly they had little mental duels, where they would write down a 'secret' on a scrap of paper, and their opponent had to somehow find out that secret within a short time period, then they would switch roles for a period, and so on.

Maybe the aspect would be "My training gaves me nightmares... here, let me share them with you"