EF's got great points.
My only addition would be that I could see the die rating of Durability to be anything you need though.
The time limit will be incorporated in the limit itself.
You might even want to stack that Durability die with the Invulnerable SFX to REALLY make him Invulnerable while the suit is active.
Of course it will be up to the player/Watcher to make sure that the limit gets used correctly.
SHORT-DURATION INVULNERABILITY SUIT
Durability D12
SFX - Invulnerable
Limit - Exhausted
Concept...something like, the suit can take five stress inducing hits or last for three consecutive rounds before it is drained of all power (player activates Limit)...but power fluctuations can occur (watcher activate's Limit early).
This would be a guy that, for a few seconds, could take whatever a god could dish out. Of course when that protection goes down, I sure hope the character has an exit strategy...
