Ess Nelek, Hero of the Hive

{1}{r}{t}: Create a 1/1 red Sliver creature token.
Whenever Ess Nelek deals combat damage to a player, put a +1/+1 counter on each Sliver you control.
At the beginning of each end step, if the total power among Slivers you control is 18 or greater, transform into Ess Nelek, Protector of the Hive.