This card seems like a game breaker in a Lannister Martell deck. Use The intrigue of both houses to gain card comtrol then on turn 6 or 7 when most of your plots are used and viola game over if you can secure 8 power in the turns building up. Iron throne and Lannister gold helps ensure dominance wins until you pull this off.
RRG pg 15 "When a player reveals the final card of his or her plot deck, after all just revealed plot cards have entered play and all necessary 'When revealed' abilities have resolved, each plot card in that player's used pile is returned to his or her plot deck."
So with a standard 7-card plot deck, the most power you can gain will be 5 power on turn 6.