After completing the Titan's Trials (missions 35-51), Adamantortoises will be replaced by Long Guis on Gran Pulse. These enemies are very tough and are immune to the instant death portion of Vanille's Death spell. You will need to prepare somewhat before trying to take these foes on. The first thing you will want to do is have your three characters' main roles maxed out at level 5, which is possible only after beating the final boss. You will want to set up your characters' Paradigms as follows (this strategy uses Fang, Lightning and Vanille); make sure you have Sprint Shoes on all your characters and a Genji Gauntlet on Fang, as well as Tier 2 or 3 weapons and Gaian Rings (this will help reduce the damage done by some of its attacks): 1) Sentinel/Sentinel/Sentinel 2) Saboteur/Saboteur/Saboteur 3) Synergist/Synergist/Synergist 4) Ravager/Ravager/Ravager 5) Commando/Commando/Commando 6) Medic/Medic/Medic You'll want to start out in #1 to survive the initial attack of Long Gui at the beginning of the battle, and make sure you switch to this Paradigm whenever the Long Gui is about to attack to minimize the damage (#6 is there to heal anytime you need it, which will be often with how damaging its attacks are). Switch to #2 and get Slow on him to reduce the frequency of his attacks, then stick one of his legs with Deshell, Deprotect, and Bio. Switch to #3 just long enough to get Enfire on Fang, then switch to #4 to get the Stagger gauge broken (on the debuffed leg) and up to 999.9% (may not need to go that high), which you should then use Highwind with Fang to pretty much instantly take out the debuffed leg. Repeat this process on the second leg and the Long Gui should fall down. With the Long Gui on the ground, quickly switch to #2 to debuff him, making sure you get Deprotect, Deshell, Bio and Imperil on him. Switch to #3 to buff your team, making sure you get Haste, Bravery, and Enfire on your team. Once that is done, switch to #4 and quickly get the Stagger gauge up to 999.9% and then switch to #5 to start whittling down its HP. The Long Gui will most likely stand up before you're able to kill it (get a Highwind off before it completely stands up with Fang), so repeat the process and you should hopefully take it out on the second pass.