Grizzled Angler // Grisly Anglerfish

Creature — Human

: Mill two cards. Then if there is a colorless creature card in your graveyard, transform Grizzled Angler.

2/3

Creature — Eldrazi Fish

: Creatures your opponents control attack this turn if able.

4/5

2016-07-13:
If you have a colorless creature card in your graveyard while you control Grizzled Angler, it won’t transform yet. It only transforms while its activated ability is resolving.
2016-07-13:
For more information on double-faced cards, see the Shadows over Innistrad mechanics article (http://magic.wizards.com/en/articles/archive/feature/shadows-over-innistrad-mechanics).
2016-07-13:
If a creature affected by Grisly Anglerfish’s effect hasn’t been under its controller’s control since the turn began, is tapped, or is affected by a spell or ability that says it can’t attack, then it doesn’t attack. If there’s a cost associated with having that creature attack, its controller isn’t forced to pay that cost, so it doesn’t have to attack in that case either.