Ivern, Slumbering Doom

Ivern enters the battlefield tapped with 2 stun counters.
Whenever Ivern enters the battlefield or attacks, choose one or both:
-Each player discards a card. Then you create a
1/1 Warlock creature token
-Each player may sacrifice a creature. Gain 2 life
for each player who does, draw a card for each player who doesn't.