Rules FAQ
- Zollo only works when a player "gains" gold, which means whenever that player takes gold from the treasury and adds it to his or her gold pool. He does not work with cards that "move" gold, or with cards that place gold on other cards.
Dothraki. Mercenary.
Reaction: After an opponent gains gold, if it is not the marshaling phase, sacrifice Zollo the Fat to move all gold from that player's gold pool to your own.
Link: Decklists
Rules FAQ