House Tyrell. Non-Loyal.
Character. Cost: 3. STR: 2.

House Hightower. Spy.

Ambush (3).

Reaction: After Hightower Spy enters play, choose a character and reveal the top card of your deck. Until the end of the phase, that character gets +X STR. X is the printed cost of the revealed card.

Torbjörn Källström
Favor of the Old Gods #63.

Link: Decklists

Hightower Spy

Rules FAQ

The character who will receive the strength boost is chosen before the top card of the deck is revealed.