Blizzard strongly advises players to not attempt Ouro in Temple of Ahn'Qiarj because of two bugs related to the encounter. As of right now, Ouro sometimes spawns an additional copy of the boss after a submerge phase! Blizzard suggests waiting until after this issue is resolved before attempting the boss.
We wanted to highlight specifically here to raise awareness of these issues for groups on Hardcore realms attempting this boss. One of these bugs has a very high liklihood to cause a raid wipe.