You succeeded where I failed. Maybe you can show this failure how it's done.
Cor Leonis
Cor is an optional boss in Final Fantasy XV: Episode Gladiolus, available to fight from the DLC's title screen after finishing it, listed as "Final Trial". It is the hardest challenge of the DLC.
Battle[]
Cor is strong and swift. He usually starts the fight with the "you're mine"/"no quarter" attack, but sometimes starts with shurikens. After this, he will fight regularly while occasionally using his own teamwork attacks from when he is a guest in the base game.
His attacks can be blocked when he is not glowing red, and blocking in the last moment opens up opportunities to parry. Successful parries of most attacks put Cor in Vulnerable state, during which he takes increased damage and doesn't attack. Typically, the player can get in four attacks, or three and a Glaive Art, after parrying. Blocking and parrying Cor's normal attacks boosts the rage meter, increasing Gladiolus's damage output.
When Cor glows red, his attacks will shatter Gladiolus's shield and some can easily kill him in one hit. Cor has various attacks at his disposal, but his most devastating one is where he draws out his katana for a powerful slash. He also throws small shurikens for ranged damage. He can be hard to hit as he often dodges and Gladiolus's attacks are rather slow. When he is in low HP, he glows red consistently with only small windows without it, so if the player can land a good parry and Glaive Art on a Vulnerable Cor when he has around half of his health left, they can skip through some of the harder parts of the battle.
The player is given three Potions and one Phoenix Down for the battle, and Gladiolus's gear is locked.
Attacks[]
"You're mine" or "No quarter" is a two-stage attack of wide horizontal slashes, with a long delay between the line and taking damage. The first slash can be parried, which will interrupt the attack and make Cor Vulnerable. The second is unblockable and must be dodged if the player fails to parry, or they will take minor damage.
"Fall" is a non-blockable attack where Cor jumps into the air and slams back down nearby, creating a small linear shockwave. It can almost always be evaded with a dodge roll. After using "fall" (or sometimes another attack, such as "hard and fast", and not always telegraphed), Cor will be unblockable (red glow) for a significant period of time and use several different attacks, including repeated shurikens and a fast close-in attack.
Cor will sometimes throw shurikens, which are usually telegraphed with blue particles with a delay before he throws. These can be parried and Gladiolus can move a significant distance toward Cor to counterattack.
Cor has a few sets of quick, low-damage melee attacks. These can easily be blocked and countered with forward+attack for easy chip damage.
Cor has at least two variants of an overhead slash, which can be telegraphed with "too slow" or "hard and fast" and can create a linear shockwave. These are easily blocked and, ironically, Cor is slow to recover from them so the player can often get in two hits.
"Pathetic" is a single horizontal slash similar to "you're mine"/"no quarter", but with a shorter reaction time and particles similar to the shuriken attack. It is dangerous when Cor is glowing red and is not always telegraphed. It has a longer recovery time like the overhead slashes.
Cor has one rare attack that will give a "Block" prompt. This works like in the main game (essentially a parry) and is a great opportunity to get in a lot of damage.
Strategy[]
Parrying Cor's attacks is the best way to take him down. The player should still aim to block Cor's attacks to avoid damage when he is not red, but parries are superior at building rage. After blocking (not parrying) the player can press forward and the attack button to perform a lunging strike that is fast and almost sure to hit without incurring damage, although it doesn't do huge damage.
The player should try to trigger a parry by guarding at the last second. The player should not parry amid a melee combo because Cor will dodge it. The player should try to raise the shield on the first attack of a melee combo, as this parry will hit and make Cor Vulnerable. When Cor is throwing shurikens, the player can parry no matter the distance. When Cor is throwing, the player should try to get close to him and parry, as Cor won't dodge.
When the rage meter is 3x or 4x, Gladiolus should use a Glaive Art. Pulling off a parry can be rare, so the player should simply use any Art they have rather than wait for Maelstrom. A Vulnerable Cor after a parry is the perfect time to use them, but as the rage drops quickly from 4x, it may be good to unleash an Art then no matter the battle phase to make use of it.
When Cor has a red glow, it is best to stay away and not engage him. If Cor gets close, the player needs to dodge rather than use the shield. (It's easiest to dodge by releasing lock-on.) It is best to try to fight Cor into one end of the field before he glows red to have plenty of room to dodge. Moving horizontally or diagonally is best to avoid his shurikens—if he hits Gladiolus, Cor can close in quickly. It is still possible to escape if he gets close, such as by rolling in the opposite direction. He will end with a couple of his strong attacks, often saying "it's over", and then the player can approach him again.
It is best not to block when there is no need to; if the blue bar below Gladiolus's health runs out, he will become Vulnerable. It recovers quickly when not blocking.
When Cor is monologuing he will often suddenly go into red glow mode afterward. When he is moving around and not attacking (usually after his quick melee attacks), that is the best time to use a potion if needed.
