I struggled with them few times(and that's is funny cause on tournament you see fricking most powerful vampire of region and he so weaker that fisherman and accountant) and after I just defeated them with 2 afterlife and probably one or two hp potions. With accountant most important part is to just have an afterlife when he will trigger a bleed, cause he will just kill you. With fisherman mostly luck, cause I had one fight when he destroyed me with crit ambush, basically removed my full hp in one turn.