Instant, 2R (3) Choose one - Creatures target player controls attack this turn if able; or creatures you control gain first strike until end of turn. Entwine {2} (Choose both if you pay the entwine cost.)1
Illus. Alex Horley-Orlandelli
8/1/2008: A creature required to attack or block if able in a given turn only has to do so during the first combat phase that turn in which it's able. Basically, each combat phase in that turn, you ask "did this creature attack/block this turn?" and "can this creature attack/block this phase?" If the answers are "no" and "yes" respectively, then it must attack or block as required. This is important if a turn somehow gains extra combat phases.