How many factions are there?

First, you need to come up with all the logical factions, and only then propose additional projects – it’s right to say that a Swamp faction with lizardmen is needed, but it’s already been cut down so much that it will be difficult to create, then Dungeon – not elves, but the second legitimate underground inhabitants – troglodytes, trolls, medusas (more correctly called gorgons), beholder, manticore, etc... Further, you can, of course, add elementals – but this is unlikely... this is according to Ubisoft's canons and laws...

And now it's time to come up with the most optimal options – the much-discussed underwater faction, evil mages (aka an ice castle with ice dragons)... well, and then you can add at most one more faction of elves and various Khajiit, Gnolls, etc... :)