I presume that if you fight with more than one enemy they fight together as one who has all special abilities. Am I right?

But what if that ability looks really non-delegable? Like Hydra's regeneration. If Hydra fights together with another enemy and they lose, and then I roll 1, do all enemies come alive?

Good question. I would say that only the Hydra can re-generate.

In the same vein, what about when you draw 2 monsters and you are the Dark Cultist, do you roll twice if you kill them or only once since they fought together?

Rimmer said:

This situation is not very difficult to handle. Ability to regenerate is valid for the Hydra only. If a Character wins against Goblin + Hydra and the latter regenerates, the combat is considered a stand-off (turn ends) but the Goblin is still killed and can be taken as a trophy.

There was a similar question regarding the Living Statue in the Dungeon and it was ruled that if you don't have a Magic Weapon to kill the Statue, the Enemies fighting together are not "protected" by the Statue's ability.

As a general Rule, the texts of Enemy cards don't combine if not stated otherwise. Each effect should be solved per se. The problem is when the effects of two cards contradict each other (e.g. the Harpy and Earth Elemental as multiple Enemies in the Highland Expansion, as pointed out in another thread).

Vampire bats fight together with the second enemy, so it is only one battle which you have to win with a gap of 2.

Rimmer said:

But if I win with a gap lesser than 2 I still have beaten the other enemy, right?

Cynewulf said:

I would say yes. The same as with the hydra or the troll if they regenerate.

The Wizard said:

No, it's not the same. For Cave Troll & Hydra you roll after winning the combat; you already killed the Enemies and see if one regenerates. Enemies that don't have the ability to regenerate stay dead, but if Cave Troll regenerates, it's a stand-off and turn ends.

Vampire Bats affect the result of combat ; if you don't roll a combat score with 2 extra points over your opponents, you don't win. The bats make combat even more difficult if they're faced together with another Craft Enemy. The same for simple monsters like Pack of Wolves or Goblin Trapsmith, whose influence on combat score can be determinating against multiple Enemies.

The_Warlock said:

Yes of couse

The Dark Cultist only rolls for one gift when fighting two monsters as one combat, so sayeth the official FAQ.