In World of Warcraft: Legion we run into several new varieties of elves that happened to survive the War of the Ancients. One sub-species were called the 'fal'dorei': half-elf, half-spider (think driders from D&D). They were mutated as they retreated from the destruction of the Well of Eternity. This sounds very similar to another situation: the naga. They were sinking and an Old God (N'Zoth) had transformed them into their serpentine forms.
However, when playing through the quests that involved them, I didn't see any information. Is there something I'm missing, were these spider elf hybrids created by the old gods, or did something else mutate them?