I noticed this while playing the She-Hulk tournament. I had triple-cast She-Hulk’s green to drain the enemy of AP, and then cast Mordo’s purple. The following error showed up:
NOT ENOUGH AP
Your team doesn’t have enough AP to use that power!
Of course, it is the enemy team that doesn’t have enough AP for my power to actually do damage: I had enough AP to theoretically use the power.
[and yes, I realise it would have made more sense to use Mordo’s power first]
//Edited Title -Brigby