Discussion about Dungeon (Dark Elves).

No, Psionic is right, the second hero is indeed essential, especially at the beginning. It doesn't matter if he's just a supporting hero, a serious additional hero, or even becomes the main hero; in the latter case, a third native hero would be helpful. First, it's about the units; if you're lucky and an additional hero like Vaishan appears, every stalker becomes valuable. Second, it's about saving turns; believe me, I've encountered situations with all races where a few extra turns were needed, and this is more common with the Fortress faction due to the specific tactics.
Also, Kifrah is noteworthy; she's not only an excellent supporting hero (specializing in melee minotaurs and, most importantly, providing 250 gold to the treasury), but due to her Stone Skin skill, she can become an excellent main hero against the Mechanoids (I recently tested this, and it works well), and there's also the element of surprise; they won't expect her.