Origin of the Avengers

Legal in Standard, Pioneer, Modern, Legacy, Vintage, Commander

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Scry 2.
II — You may put a Hero creature card with mana value 3 or less from your hand onto the battlefield. If you don't, draw a card.
III — Put a +1/+1 counter on each creature you control.