If a monster attacks a free space and rolls 2 power surges can the overlord gain threat points?

Meridian said:

Q: Under what circumstances can the overlord receive threat for rolling surges on an attack roll?
A: The overlord may spend two surges on each attack roll to gain one threat. He may do this on any attack that hits a hero. This represents a change from previous FAQ rulings on this subject.

No, you need to actually have the attack hit a Hero to be able to spend the surges to get threat.

Thank you; I' feel sorry not to have read FAQ about this question.

I presume this FAQ should be applied in the reverse, for cases where the Heroes get the gauntlets that recover 1 fatigue for each 2 surges, they only regain the fatigue if the rolled surges were in a non-miss attack?

FAQ page 4:

Q: Can heroes attack an empty square? For example, could a blast effect be centered in an empty square or could a hero fire his Staff of Knowledge off into a corner to burn the overlord’s threat?
A: Yes. However, if after spending surges there are no valid targets in the area of the attack (hero or monster), the entire attack is canceled without effect. This means that if the blast is not large enough, the attack fails, and the Staff of Knowledge must actually hit something to use its ability.

So the current ruling seems to require that you hit something in order to spend surges on (e.g.) the Gauntlets of Power, but they don't require that the thing you hit be a monster, contrary to the rule for the OL generating threat where he specifically has to hit a hero.

Not that I would be in the least bit surprised if that difference were entirely accidental...

Let me make sure I am playing correctly...

So as overlord,

a) if I roll a miss I would not collect surges.

b) If I hit, regardless of damage, I can collect 1 threat for every 2 surges (or every surge if using Dark Prayer.)

You need to specifically hit a hero with the attack, and units with Dark Prayer gain bonus range and damage for each surge in addition to the threat, but other than that, you're correct.