One magic spider boi

Oh yeah dhoulmagus second form can be brutal however there is a way to make it easier if you have the patience to level grind (the fastest way at that point in the game is the forest near the argonian royal hunting ground metal slimes are fairly common there and they tend to spawn in groups of at least 3 and it's not uncommon for groups of 8 to spawn.) You can get angelo to level 30 where he'll learn multiheal which makes the battle much more bearable since it heals at least 100HP to the entire party, if not then I'd suggest: equipment that reduces damage from breath based attacks especially ice since his ice breath attack can do up around 60 to 76 points of damage and insulate which Jessica learns at level 25, surprisingly enough second form dhoulmagus only uses icy wave every few turns so you can buff up your party at least a bit I recommend oomphing yangus and having him use helm splitter not only will it do a good amount of damage it also has a chance to decrease the boss's defense making it easier to damage him, if you have a monster team then you can summon them at the beginning of the battle for the best results I'd recommend talos, dumbking, and hackzilla if you're lucky dumbking will oomph talos first which will allow him to do a good amount of damage before they leave due to the turn limit, I'd also recommend that both the hero and angelo know fullheal and that you have Jessica carry at least one or two ygdrassil dews (made with a ygdrassil leaf + magic water) in case of an emergency.Dhoulmagus is definitely the game's way of telling you that "You'd better be overprepared from now on because I'm not holding back anymore!"