(Oddly specific trope) Evil purple/pink materials

Petrified Darkness (Skylanders): Turns people into stronger and eviler versions of themselves

Dark Energon (Transformers: Prime): Brings dead Cybertronians back as zombies, turns regular machines into monsters, and can make living Cybertronians stronger, but also more aggressive

Element (Ark): Able to corrupt and mutate creatures, and force most of them to mindlessly attack anything in sight