Flying When Foe-Razer Regent enters the battlefield, you may have it fight target creature you don't control. Whenever a creature you control fights, put two +1/+1 counters on it at the beginning of the next end step.
You choose the target of the first triggered ability as it goes on the stack, but you choose whether or not to fight as that ability resolves.
If the target creature you don't control becomes an illegal target of the first triggered ability before it resolves, Foe-Razer Regent won't fight and its last ability won't trigger.
If a creature you control fights during an end step, the delayed triggered ability that puts +1/+1 counters on that creature won't trigger until the beginning of the following turn's end step.