Mad Alchemist doesn’t have much health, but he does spawn a lot of adds who can freeze you in place and do poison damage. Try equipping a weapon, like a bullwhip, that can deal damage above the character, or using spells that you can aim into him from below. Also try hitting him while standing beside him at the outer edge of the arena so that his thrown spells miss you. To make the fight faster, use something that does additional damage over time, like poison.
– Laura Michet, resident Salt and Sanctuary expert