Ellana, Queen of Asigol

Flying, first strike, deathtouch
Whenever Ellana, Queen of Asigol enters the battlefield or attacks, put two 2/2 black Skeleton creature tokens onto the battlefield.
If you control six or more skeleton creatures, you may sacrifice all skeleton creatures you control. If you do, put a 9/9 black skeleton creature token with undying and deathtouch named Ellana's Liege into play.