
Gotta just get down and dirty with this one. You get 724 EXP and 198 Sx when you defeat them. Beware of his minions frequently using the Heal spell, an easy way to stop this is to simply Silence them (as an aside, these are the exact same minions in the dungeon so things like Flirt also work). He has a good punch, but is vulnerable to the Poisoned Blade. You get as much as 1,748 EXP and 316 Sx for your efforts. Just setup your team to take advantage of the enemies you fought in the dungeon (my preference being Simon, Yarra, Aka, Robin). Portal Demon summons the enemies that you already fought and killed in the dungeon, with its only real threat is allowing it to live for (far too many) turns where it will hit you with a very powerful AoE that might even one-shot some characters. It's entirely possible to solo this with Simon but you'll piss off the girls (and rightfully so). Provided that your entire party is in good health, you shouldn't have any kind of troubles with him. Battlefield Medicine removes the status effect if it becomes necessary. It does have an AoE Poison attack, but it's also immune to Silence meaning you're going to have to endure it. Coupled with Blind (which it resists slightly), its damage output is reduced severely. The Chimera's main attacks all revolve around physical offense, so Aka's Weakening Stab reduces its damage output a lot.

There's a minor fight before you are allowed to heal via the camp again so make sure that your party is healthy enough so it can survive that as well (approximately half health on everyone should be fine). Simon's Silencing Strike will remove a lot of its damage threat, inflicting Blind with either Simon's Blinding Strike or Aka's Blinding Stab will remove the rest of it. It will spawn after Yarra joins the party. Also remove your equipment beforehand, because the fight will end faster and you will retain Tal's and Altina's gear. She is much too strong to be defeated at that point in the game (except by cheating and even then they give 0 EXP/Sx), so the best advice is that you should not spend any of your consumables on this hopeless fight.

Your little party has to beat two Elite Succubi and a powerful succubus mage.
