So I just had a bit of a dispute with somaddict about whether my forcemaster could reveal Mind Control on an opponent's Grizzly immediately after I was done with her action phase. Somaddict is convinced that the "action phase" always refers to the overall section of the round in which all creatures use actions, and that it never refers to the specific action phase of an individual creature. This caused him to think that Mind Control could only be revealed after ALL creatures were done acting for the round, and he got REALLY ANGRY that I didn't agree with him (that's a huge understatement, but I'm not going to go into detail about the very nasty things he said).
It just doesn't make sense to me that Mind Control, a high mana cost high level spell, supposedly a "powerful" spell, would have such a choking restriction. I've recently read a thread where it was said that most enchantments can be revealed between steps of another creature's action phase, and I think what's intended with mind control is that it can't do that, but can still be revealed between the action phases of two separate creatures in the same round.
Is there any concrete official ruling on this? Specifically something that clears up the confusion about "the Action Phase" and "a creature's action phase"?