401. Exhaust

401.1. Exhausting is an action that marks a non-spell Game Object as "spent."

401.1.a. To mark it, rotate the card 90 degrees opposite of Readying , so that the orientation of the card is lengthwise in front of you.
401.1.b. A Unit that is already Exhausted cannot be Exhausted again.
401.1.c. If a Unit is instructed to be Exhausted while it is already Exhausted , nothing additional happens.

401.2. "Exhausted" is a state for Game Objects that other game effects and rules can reference.

401.3. This is a Limited Action.

401.3.a. Most Exhaust actions will be costs for Activated Abilities or Discretionary Actions. Example: A unit's Standard Move exhausts the unit as a cost.

401.4. When Exhausting is listed as a Cost , then the Action must be able to be completed for the cost to be paid. Example: A spell says "As an additional cost to play this, you may exhaust a friendly unit." An exhausted friendly unit may not be exhausted again as the additional cost for the spell, and the additional cost has not been paid.

401.5. In abilities, the Exhaust symbol represents the cost "Exhaust this" or "Exhaust me." It resembles a card turning sideways.