I`m using Grisban and I`m imobilized. I don`t have any used fatigue. Can I use his heroic ability to get rid of the condition?

I dont have the card in front of me. But, I believe his ability says when you take a rest action, remove conditions. So, since rest doesn't require you to be short any fatigue, yes, you can use the ability at full fatigue.

Lex Hobby Store said:

Grisban's hero ability doesn't usefully get rid of immobilize even if he does have fatigue. Grisban removes conditions when he "recover fatigue from performing a rest action". Rest actions recover fatigue at the end of a hero's turn so when Grisban rests he can discard a condition card at the end of the turn at the exact same time immobilize goes away on it's own.

The ability says: " Each time you recover fatigue from performing a rest action, you may also discard 1 Condition from yourself".

Lex Hobby Store said:

Well, from that wording, I would say that he would need to at least recover 1 fatigue to use that ability. So I take back my previous statement and would say, no, you cannot recover zero fatigue.

Grisban's ability removes the condition at the same time as you remove the fatigue.

Consider the conditions:

• Immobilize - Clears at the end of the turn.
• Stun - Prevents Grisban from taking a rest action unless this is cleared first, so his ability can only clear a stun if it was placed on him during his 2nd action.
• Poison - Can be cleared with a strength test. Since Grisban has strength 5, this is easy to clear (92% chance).
• Disease - Can be cleared with a willpower test. Grisban's willpower is 3, so this is harder to clear (53% chance) without the ability.

In the end, the only times Grisban's ability can take effect are if he fails the 50/50 roll to clear Disease or runs into a Pit Trap with no movement points remaining. Until an expansion introduces more status effects, his ability is pretty near useless.