Mythic dungeons are hard, please don't expect to get carried.
I had 1 group fail out on the second Skyreach boss. Healer was undergeared and DPS absolutely refused to use any sort of defensive cooldowns to avoid the damage from Burst. I figured rukhran would be easy, but now that I think about it, the birds mechanic is one people usually dont pay attention to, I can see how that would wipe groups.