This boss has 3 phases. In the first phase, attack him and avoid his attacks. He has a ground pound and a laser and will summon adds. Once you get him to around a quarter or so of his health he will teleport you away. In this phase you will be in an area surrounded by the corruption under a bubble created by one of the spirits you rescued. You must stay in the bubble as you search for you family members that need reviving. There will be enemies spawning but I just ignored them unless they got to close to me. Once you find a family member follow the prompt on screen to revive them. Once you revive all of your family members, You will be teleported to the final phase of the battle. This is pretty easy as all of your family will be attacking with you so just lay into him. don't really have to dodge his attacks. Achievement should unlock after he dies.