House Greyjoy. Non-Loyal.
Event. Cost: X.

You may only use gold from the losing opponent's gold pool to pay for Loot.

Reaction: After you win an unopposed challenge, discard the top X cards from the losing opponent's deck.

Tomasz Jedruszek
No Middle Ground #73.

Link: Decklists


Rules FAQ:

mplain 211
Can Loot be played during the marshalling phase? — Statusunquo 1
If you find a way to win unopposed challenge during marshaling, sure. There's no way to do that currently. — ltlukoziuz 4