What would be a good passive ability that could tie in with a creature that could only self-antimatter?
Why self antimattering? I would need a mechanical reason to give mechanical advice.
Think of the possibilities of this! If it's self antimattering every turn, it creates buff synergies, neutralizes strong enemy attacks (if given to the enemy),
Now since it's a pendulum effect, there are even more opportunities:
when it's negative, use luciferine, lobo, or some other ability removing/replacing thing to keep them stuck at healing..
This works against overdrive (somewhat)
It overall slows down losing the game, allowing deckouts or EMs more.
Need i explain more possibilities?