Periodically teleports from one end of the dock to the other (every ~15%, can do it immediately on pull). If he targets someone too far away both sides of the docks will go up in flame as a fail script. At ~20% he will port away and you must jump in the water, which is draining away, as both docks burst in to flame. At this point both Left and Right (the Turgan) go active with 25% HP. These must be separated in order to avoid a damage amplification effect from having both AEs active at the same time. Wiping on the Turgan will reset the entire script back to the beginning with Tert.