Heroic: The Safety Dance is an end game raid achievement that requires all members in the group to stay alive during the encounter with Combat . Completing this achievement is criteria for the meta achievement 16px .
The only difficulty in this achievement is having all the members of the raid being able to move across the floor in the second phase without getting hit by the waves and dying as a result. Now that the safe spot has been fixed, the only way to do this fight is simply by having everyone in the raid successfully dance through the lava stages. Since Heigan puts out such low damage and has no enrage timer, you may find it easiest to do this achievement with a reduced-size raid.