The use of Tortoise Song will dispel 3 buffs, including food, from all targets within 20'.
Casts various Earth and Water elemental magic, including -ga V.
Head Butt knocks back quite far, and applies a powerful Defense Down debuff.
Harden Shell grants a significant reduction in damage taken until dispelled.
Earth Breath has a 3 second charge-up time. Can easily move to side if you are its current target to avoid getting hit for full damage. Other players should avoid standing in front at all times.
Aqua Breath is nearly instant, making it much harder to move away from, but deals less damage than Earth Breath (about half).
At 75%, 50%, 25%, 10%, and 5%, it will retreat within its shell and regenerate at an accelerated rate for about 20% of its total life. Will Draw-In its current target repeatedly if they are outside of melee range during this period.
High ice damage (from spells or skillchains) whilst in its shell has a chance to , cancelling the regen and causing it to come out of its shell.
Upon exiting its shell, it will Draw-In everyone to directly in front of it, followed by either Earth Breath, or Aqua Breath.
If it chooses Earth Breath, everyone should move to the side to prevent significant, if not fatal damage.
If it chooses Aqua Breath, it should be survivable assuming everyone is at full health, and has a good Damage Taken gearset.