Exhaust

Exhaust is a mechanic introduced in Aetherdrift. It signifies activated abilities that can only be used once.
==Description==
Exhaust is a keyword action, as the ability could do any number of actions, all of them adjoined by occurring only once. This term of phrase is reminiscent of Monstrosity, another activated ability that is intended to be used only once. That ability used a designation to mark the usage of the ability, but later cards such as <c>Mild-Mannered Librarian</c> signified this unnecessary, suggesting a precursor to this ability. However, not all Exhaust abilities use mana nor generate +1/+1 counters, though they usually have an easy way to remember that they've been activated.
==Rules==
==Rulings==
*If a permanent with an exhaust ability that's already been activated leaves the battlefield and then returns, it's a new object with a new instance of its exhaust ability. That exhaust ability can be activated.
==Examples==
==References==