rise of the gatewatch

When rise of the gatewatch enters the battlefield you gain 7 life , deal 7 damage to any target and search your library for seven cards.
Reveal those 7 cards and choose 3 to put in your hand and put the rest in your graveyard.
Create 3 4/4 black eldrazi creature tokens with"{t}sacrifice this creature.deal 3 damage to any target.
" And it was then they realized that they were one"