Snow White

Whenever a dwarf enters the battlefield, put a
+1/+1 counter on Snow White.
{r}{w}{u}{t}: Search your library for a dwarf
creature card and put it onto the battlefield.
{x}{r}{t}: Deal {x} damage to any target
where {x} is how many dwarfs are on your
battlefield, divided by 2 and rounded down.
Activated abilities of Snow White can only
be used once each turn.