Exhaust

[["Keyword Ability",[{"data":"[[Activated ability|Activated]]","label":"Type"},{"data":"''[[Aetherdrift]]''","label":"Introduced"},{"data":"''[[Alchemy: Tarkir]]''","label":"Last used"},{"data":"Exhaust ''(Activate each exhaust ability only once.)''","label":"Reminder Text"},{"data":"3","label":"[[Storm Scale]]"},{"data":"29  cards[[File:U.svg|x15px|alt={U}|link=]] 24.1% [[File:R.svg|x15px|alt={R}|link=]] 20.7% [[File:G.svg|x15px|alt={G}|link=]] 20.7% [[File:UB.svg|x15px|alt={U/B}|link=]] 3.4% [[File:RG.svg|x15px|alt={R/G}|link=]] 10.3% [[File:GU.svg|x15px|alt={G/U}|link=]] 6.9% [[File:M.svg|x15px|alt={M}|link=]] 6.9% [[File:artifact symbol.svg|x15px|alt={artifact symbol}|link=]] 6.9% ","label":"Statistics"}]],["Scryfall Search",[{"data":"[https://scryfall.com/search?q=keyword%3A%22Exhaust%22 keyword:\"Exhaust\"]"}]]]

Exhaust
Keyword Ability
Type	Activated
Introduced	Aetherdrift
Last used	Alchemy: Tarkir
Reminder Text	Exhaust (Activate each exhaust ability only once.)
Storm Scale	3
Statistics	29 cards 24.1% 20.7% 20.7% 3.4% 10.3% 6.9% 6.9% 6.9%
Scryfall Search
keyword:"Exhaust"

Exhaust is a keyword ability introduced in Aetherdrift. It signifies activated abilities that can only be used once per game.

Description

Exhaust is a unique type of keyword ability where "Exhaust — [Cost]: [Effect]" means "[Cost]: [Effect]. Activate this ability only once." 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. However, Exhaust is worded in a way that lets it resolve your ability without interruption, while the "becomes Monstrous" ability can fail if the creature dies mid-activation. That ability used a designation to mark the usage of the ability, but later cards such as Mild-Mannered Librarian signified this unnecessary, suggesting a precursor to this ability.

Almost all cards with Exhaust are creatures and use counters to track once they've been activated. Five cards don't use counters as a marker and track them differently: Draconatics Engineer creates a token, Winter, Cursed Rider exiled artifacts, and Riverchurn Monument would typically put a large number of cards into a graveyard. Redshift, Rocketeer Chief has an ability that rarely needs or warrants activating twice. Loot, the Pathfinder is the only one that has no designed tracker and also has three Exhaust abilities.

History

The first card to grant an ability that only could be used once was Touch of Vitae (Ice Age), an instant. Commander 2017 was the first set to feature a card with the explicit clause that it only could be activated once: Stalking Leonin. Since then, similar phrased cards have been released regularly. There are no plans to reactively errata those cards to give exhaust.

Rules

From the glossary of the Comprehensive Rules (April 4, 2025—Tarkir: Dragonstorm)

Exhaust

A special kind of activated ability that may be activated only once. See rule 702.177, “Exhaust.”

From the Comprehensive Rules (April 4, 2025—Tarkir: Dragonstorm)

• 702.177. Exhaust
  • 702.177a An exhaust ability is a special kind of activated ability. “Exhaust — [Cost]: [Effect]” means “[Cost]: [Effect]. Activate only once.”
  • 702.177b An effect may allow you to take an action as long as you haven’t activated an exhaust ability this turn. Such an effect allows that action only if you haven’t begun to activate an exhaust ability this turn.

    Example: Elvish Refueler has an exhaust ability that costs mana and also has an ability that reads “During your turn, as long as you haven’t activated an exhaust ability this turn, you may activate exhaust abilities as though they haven’t been activated.” Loot, the Pathfinder has an exhaust ability that is also a mana ability. If you’ve already activated both of these abilities in a previous turn, you can’t activate Loot’s mana ability during the process of activating Elvish Refueler’s exhaust ability, because you have already begun to activate a different exhaust ability.

Rulings

• 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 (e.g. flickered), it becomes a new object so its exhaust ability can be activated again.
• If an ability triggers whenever you activate an exhaust ability, that ability resolves before the exhaust ability resolves.

Examples

Example

Prowcatcher Specialist
Creature — Goblin Warrior
2/1
Haste
Exhaust — : Put two +1/+1 counters on this creature. (Activate each exhaust ability only once.)