Buy @ TCGplayer
Destroy target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
If the creature regenerates or has indestructible when Spread the Sickness resolves, you’ll still proliferate.
If the creature is an illegal target when Spread the Sickness tries to resolve, the spell doesn’t resolve. You won’t proliferate.
