Peema Trailblazer

Exhaust abilities can be activated any time you could normally activate an ability.

If an exhaust ability of a permanent is activated, and then that permanent leaves the battlefield and returns to the battlefield, it becomes a new object so its exhaust ability can be activated again.

Some spells and abilities which give you energy or say you “may pay” some amount of energy require one or more targets. If each target chosen is an illegal target as that spell or ability tries to resolve, it won’t resolve. None of its effects will happen, you won’t get any energy from it, and you won’t get the chance to pay any energy for its effects even if you want to.