War of the Ring: Official FAQ Master! Webmaster of www.warofthering.eu Author of the War of the Ring Companion
- This is My Hour!
Here is my take one it:
The card can be played as long as a Minion is in the battle.
If GtW has negated any Nazgûl Leadership which was present then the Shadow player is unable to forfeit his ENTIRE Leadership (which is required by the card). Therefor the card becomes useless (but still playable as long as a Minion is present).