Optional: Gael
Maximum souls: 892,296
Gael is weak against these: poison, toxic, lightning. The weapon art of the Storyteller's Staff is a more potent and long-lasting poison than Poison Mist. He is also weak against frost, but after frost damage is activated you must use a fire weapon against him for his frost bar to be depleted (or wait for the bar to slowly decrease). The boss can be bled, although you should consider using a blood infused weapon to bleed Gael.
In the 1st phase, poison Gael with Poison Mist or the weapon art of the Storyteller's Staff. You also have the choice to toxic him with Toxic Mist or Dung Pie. The Poison Rotten Ghru Dagger+10 is also effective for poisoning Gael. Once he is inflicted with poison (and/or toxic), switch to your main offensive weapon. Consider using an ultra greatsword to poise damage Gael. Depending on your stats, a fully charged R2 of the Fume Ultra Greatsword or the Lothric Knight Greatsword can stagger him. Two-hand your ultra greatsword. As he prepares to carry out his combo and finish off with a jump where he thrusts his weapon into the ground, be prepared to roll into Gael before he thrusts his weapon and fully charge your R2 attack to stagger him. A straight sword buffed with lightning is also effective, e.g. a Sunlight Straight Sword+5 buffed with Lightning Blade by using Yorshka's Chime+10. A bleed weapon is also effective, e.g. Blood Bandit's Knife+10.
In the 2nd and 3rd phases, poison and/or toxic Gael again then switch to your main offensive weapon. A greatsword or ultra greatsword might not be as effective as in the 1st phase because of his various new combos and AOE attacks. Consider using a fast weapon such as a straight sword or a dagger. Poison Throwing Knife also helps to poison the boss and to chip down his HP bar. The above strategy is demonstrated in the following video.
Gael NG+32 poison & bleed, Dark Souls III
All 3 phases of Gael can easily cheesed. Lure Gael to a certain spot as shown in the video below, then run behind a fallen building, cast poison and toxic through the building. Using the weapon art of the Storyteller's Staff can be trickier than using the Poison and Toxic pyromancies.
