These are the actions that a Champion can perform on its turn:
Any action except the Move, ends the Champion turn immediately.
When a Champion tries to move out of a Champion/Monster RNG area, it will suffer an Opportunity Attack from it. It's a normal attack, but the "running" Champion has a +2 DEF bonus.
The attack was a disaster and you hurt yourself. The Attacker applies 50% of its DMG (round down) on its own LP.
The attack failed causing no effects.