Two possibilites:
A firefly was mutated, and it had Dejavu as an ability. After using it, an ability-less Firefly remained.
It was then Antimattered and Blessed until it had 0 attack.
Very close.
It was a mutant, and Antimatter was used on it. Blessing/Rage/Chaos Power was not used.
Lycanthropy + Antimatter + ATK buffs?
You pretty much got it, but you put in an extra step.
Antimattered a 5|3 mutant which then used Lycanthropy.