Biologist's Potion

When Biologist's Potion enters the battlefield, put a +1/+1 counter on target permanent.
When Biologist's Potion is put into your graveyard from the battlefield, proliferate. (You choose any number of permanents and/or players with counters on them, then give each another counter of a kind already there.)
{3}, {t}: Sacrifice Biologist's Potion.