Omega Sliver

When Omega Sliver enters the battlefield, exile
all other creatures.
For each sliver exiled this way, Omega Sliver put
+1/+1 counter. If fve slivers are exiled this way,
put a hexproof counter on Omega Sliver. If ten slivers are exiled this way, put a haste counter on
Omega Sliver. If fifteen slivers are exiled this way
put a doublestrike counter on Omega Sliver.