Graft

From Archon Arcana - The KeyForge Wiki

If a card ability instructs you to graft a card onto another card, the card being grafted is placed faceup under the other card. The grafted card is not considered to be in play. If the card onto which it is grafted leaves play, the grafted card is placed in its owner's discard pile.

Official rules v1.8 March 2021