Playing Cards

The active player may play cards of the active house during step 3 of their turn. When a card is played, the active player takes the appropriate card from their hand and does the following:

1. Reveal the card being played and confirm it is eligible to be played.
2. If the card is an action, continue to step 3. If the card is an artifact, a creature, or an upgrade, it enters play and is placed in the appropriate play area:
   • If the card is a creature, it enters play exhausted on either flank of the controlling player’s battleline.
   • If the card is an artifact, it enters play exhausted in a row below the controlling player’s battleline.
   • If the card is an upgrade, it enters play attached to a creature chosen by the active player. An upgrade can be attached to a creature controlled by either player. The upgrade is controlled by the player who played it, even if the creature to which the upgrade is attached is controlled by the opponent.
3. The card is considered “played”. Resolve bonus icons (if any) from top to bottom, one at a time.
4. Resolve “Play:” abilities, “after a card is played” abilities, and ”after a card enters play” abilities in the order of the active player’s choosing.
5. If the played card is an action card, it is placed faceup on top of the owner’s discard pile.

—KeyForge Master Rulebook v17.4 September 2024

Commentary

If a card ability allows a player to play or use another card (or to fight or to reap with a card), the chosen card may belong to any house unless the ability specifically states otherwise.

Source: Using Cards Via Other Abilities