To illustrate this imaginee a group of mobs made up of minions A, B, C and D ('A' being the front one) wanting to advance into a corridor. The goup plays a move of 3. You would expect A to move 3, then B then C and finally D, resulting in everybody advancing 3 steps- What very oftens happens is the AI trying to advance D, cant get anywhere because of groupmates. It then tries with C, who cant get anywhere,... and so on. Then finally advancing A by 3 the others in the group having wasted the moves. I
Maybe the ai doesn't get to chose - maybe it's a set order who's movement get triggered first - like the Shift, Team! and similar cards, which just triggers movement for your party members - one by one. Would be nice to be able to pick order. Might be the same issue.
Yeah, neither you nor the AI gets to choose the order. It's determined by the internal ordering of monsters within the group.
