Upcoming immortal boss?

[Rhelyo]

In Cataclysm we had Sinestra immortal feat.In MoP we had Ra-den.
I couldn't see any feat of strength yet from the bosses we know we will fight in 6.2.
So which boss you want to see as possible immortal run?

[Raugnaut]

Both Sinestra and Ra-den were heroic-only.

Currently, it seems there are no Mythic-only bosses coming out with 6.2, so we likely won't have any.