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 Tangleclaw Werewolf transforms into Fibrous Entangler while it’s attacking, having vigilance won’t cause it to become untapped.

2016-07-13 : If each creature that could block Fibrous Entangler is tapped or is affected by a spell or ability that says it can’t block, then none of them block. If there’s a cost associated with having each of those creatures block, its controller isn’t forced to pay the cost, so they don’t have to block in that case either.

2016-07-13 : Only one creature is required to block Fibrous Entangler. Other creatures may also block it, and are free to block other creatures or not block at all.

2016-07-13 : The defending player, not you, chooses which creature blocks Fibrous Entangler.