Dragon Hunter's ability: Whenever you engage an Enemy in battle, you may make a deathblow. Roll two dice and add them together to determine your attack roll. If you make a deathblow and roll doubles, you are automatically defeated regardless of your attack score.

Is he able to use a fate to reroll one of his dice used for a deathblow?

It seems to make the limitation useless, but why do you think he's not able to reroll one die of his choice with Fate?

No rule reason.

Just overpowered feeling.

Rimmer said:

In this case, you're right. Most players feel the same.

Let's see if we receive some answer, but since this is not a "rules question" we might receive none here (or just another: "yes, of course he's able").

I think that the dragon hunter can use fate as normal.

You cancel one of the die´s so you can roll again, and then you are not automatically defeated..

Note that it can also work the other way.

Say you only need to roll 4 or 5 to beat the monster (quite doable when allowed to roll two dice), but you happen to roll 1+2. Then you could use fate to reroll the 1 and get a good chance of defeating the opponent, but with a chance that you roll a 2.

Sure you can. You can still roll the same and be defeated.