He doesn;t have to be last in a turn - he has to act after every creature that is thetening him, so:
- he can go after every creature in the arena (can be easly countered, as you've proven)
- he can attack lone, weak target, which will probably die be one hit or could not make decent damage
- he can be protected with spells like Block
- Forcemaster can separate his target from the rest of the group
- Forcemaster can make potencial threats to him incapacitated
Your oponent can try to counter those situations, but this is win for you too, becouse you are the one who dictates what your oponent does.