Blorb: Shield (Weapon? Permanent? Creature even? Anything works, I guess.) that has a small chance (10%? 15%?) to turn so many attacking creatures into weak creatures. (Spark was my first idea, but we could make it Photon.)
The mechanic isn't new, see Graveyard and a certain failed rare shield. In fact, it's so good that I wanted to do it in another element. Life, for a parasite, or time, for reverse evolution.
Ideas?