Haoran

Haorun is the best healer in the game hands down due to his passive and personal skills. While many people may sleep on this man, the fact that you can get Haorun's passive skill to work on himself while having access to the class tree that he does really exacerbates how amazing he is. Both the Brightening and Prophet Ring are HUGE buffs in Demonic. If you skipped this guy because you "already had a healer", definitely try him out again. 

Tidecaller - While there are many reasons why Tidecaller is one of the best - if not just outright the best - classes, Haorun is the best candidate for it. Having access to his personal heal gives him the flexibility to do other things. His stats are just very respectable across the board and his passive gives them 2 mastery every single time they are healed by him for 4 turns. So not only is Restoring Waters obviously strong, but so is his Chain Heal. 

Spirit Keeper - There is only one reason you would want to go Spirit Keeper on Haorun and that is AoE heal Spirit Bomb. As mentioned before, His personal skill pairs well with Brightening and Prophet Rings that well. 

Blood Tide - This is a build super unique to Haorun due to his passive taking it over the top. While there's really not much point to this build, his personal and class passive works on him so he can get pretty insane mastery very early with the Plague Ring. If the enemy initiates and hits Haorun, Haorun can get this to +2 mastery 4 times in a single combat. The Calamity Ring doubles down on this letting him get yet another 2 mastery any time anything is defeated friend, foe, or ally. All in all, that's a potential 10 mastery every time a single enemy initiates hit Haorun and he kills them back. Pretty op stuff.

Spirit Taker - Similar to the Blood Tide build, Haorun wants to enter combat as much as possible, trigger the Calamity and Plague Ring heals and stack up mastery to Spirit Bomb the unfortunate souls who would stand against him. In this class, he will be significantly slower so keep that in mind.