“Heroes of Might and Magic V: Tribes of the East”

Judging by the plot, the Elves will be Elves - Elementalist, and the Dark Elves will worship demons, so the alternative upgrade will be related to them (but this is just my guess).

Regarding the elementalists, yes, judging by the scenario, there are new enemies, and druids have started summoning elementals, and they started doing this after making a deal with a Warlock.