Heishen, Mikokoro's Wake

Heishen enters the battlefield with X +1/+1 counters on it.
Whenever Heishen attacks, if its power is even, reveal the top card of your library and you may cast it without paying its mana cost if its mana value is even. If its power is odd, you may return target permanent card from your graveyard to the battlefield if its mana value is odd. If you do neither, you may draw a card.