Erevan, Bloodline Sire

Flying, Lifelink
When Erevan, Bloodline Sire enters the battlefield, create two 1/1 black Vampire creature tokens with flying and lifelink.
Whenever another Vampire enters the battlefield
under your control, you may pay X life, where X
is the power of that Vampire. If you do, put X
+1/+1 counters on Erevan, Bloodline Sire.