For the next add phase, I just make sure to have the buff maim up when garuda disappears. No point having full stacks as unchained is down. The adds spawn at the east and west. Go stand at the east of west edge of the circle and pop cooldowns when Garuda disappears. Tomahawk twice while running to the other add/your healer, heavy swing the add once then provoke skullsunder -> butcher block the other. Build a bit more agro on the add you tomahawked then you're just tanking like normal.

Hope that helps.