Otherworldly Sliver

: Whenever a Sliver would leave the battlefield exile it instead with X time counters on it, with X equal to its casting cost. It gains suspend.
+1: Sacrifice a Sliver: Each Sliver gains phasing and phases out. You may use this at instant speed but only during your turn.
-7: Sacrifice each Sliver you control. Each player mills cards equal to the combined power of the slivers sacrificed. Transform Otherworldly Sliver.