Rule 137.3

A card’s Might Bonus modulates the Might of the card to which the card that has the Might Bonus is Attached. See rule 716. Attachment for more information.

• 137.3.a The Might Bonus is applied while Attached and stops applying as soon as the card with the Might Bonus is no longer…
• 137.3.b If the card to which a card with a Might Bonus is Attached has no Might value, the Might Bonus is ignored.

Official Core Rules