Quest / Boss
The Amorphus Being
After dropping below 50% HP, Grand Jelly will use a skill called Extreme Softening, which grants it an insane defense buff to all attacks. The only way to kill it, after it does this, would be to inflict it with Poison, which deals 30,000 damage per turn for two turns. Must be re poisoned after it wears off.
Grand Jelly is an Earth element, but attacks with Water element. Mono-fire and thunder squads are not recommended.
It is possible to one-shot Grand Jelly with a mono-fire squad. For the squad, it is best to equip Muramasa, Angelic Foil, Amanohabaken or Masamune spheres.
A Leader that can nullify status ailments is the best for this dungeon because it will cause Poison, Weakness, Sickness and Curse. Leaders that can do this are Havoc Angel Ronel, Gemini Il & Mina, Hail Gigantron Reeze, Guardian Darvanshel, Void Pearl Ivris, Pumpress Semira or Crescendo Megurine Luka.
Its attacks can also lower a unit's BB gauge.
If you don't have any units that can inflict Poison, equipping units with spheres that can inflict Poison will work just as well.
Note that DEF-ignoring Leader Skills (like Legatus Melchio & Duel-SGX) and Brave Bursts (like Noble Fist Dilma) do not work against the boss once it casts Extreme Softening.
Grand Jelly has the following skills:
Liquid Solution - STBB Water (+ Earth) attack that deals a fixed 2,000 damage. Also removes unit's buffs. Will be used most often. Recommended that units have high HP.
Drink it down. - Massive single target Water (+ Earth) attack.
Decomposition - Powerful AoE Water (+ Earth) element attack.
Extreme Softening - Damage mitigation buff that causes all attacks on Grand Jelly to do 1-50 damage (casts after falling below 50% HP).
Jiggly - Warning of "Melt the World" coming soon (casts after turn 6 and turn 7).
Violently Jiggly -notification that "Melt the World" will occur next turn (casts after 8 turns)
Melt the World - Fixed 20,000 damage (casts after 9 turns) and reduces all BB gauges to 0. Mitigation and guarding or using Angel Idol and Goddess Idol is highly recommended.
General Zone Details
Unlocked after defeating Grantos in The Giant God Awakes in Giant's Ruins.
Burst Frog and 1 Gem rewarded for first time clear.