Kollan the Corpselord

When Kollan the Corpselord enters the battlefield, each creature with less power than it
gains -2/-2 until end of turn.
Whenever Kollan the Corpselord is put into a graveyard from play, create two 2/2 blue and
black Skeleton creature tokens.
Other Skeletons you control get +1/+1 for each creature named Kollan the Corpselord in play
and in all graveyards.