Going back to Colossus’ black, whenever there is no active character except for Airborne characters, the Airborne characters land early in order to take their turn.
Just like a stunned character, the enemy should be forced to miss their turn.
If the issue is you are worried the player or AI will waste AP using abilities when there are no valid targets, just give us the no valid targets warning message. I mean, if there is code in place for when the only enemy left is invisible on how the AI will use or not use abilities, there should be something in place for the Airborne status.
When all of my enemies are Airborne, that should be free turns for me to gather AP and/or heal.
So now that Nova is making the enemy Airborne, we need this bug addressed.