Got past Exdeath on Monk/Ninja/Dancer/Geomancer. Got everyone to front row and only Lenna as Ninja attacked with Air Knives for 2000 per throw. Costly, yet the only way I can imagine doing it as I've failed around 20 times before. Level 30, btw.
Got the Chicken Knife, Sword Dance does 8800 with it=p Sucks that both Geo and Dancer are luck based, otherwise they would be much, much better. Then there is always an option of giving the Knife to Ninja along with a Twin Lance - they can do over 3000 damage on monsters, even up to 4000 if their defence really sucks. Attempting the Fork Tower now. I could also use some Reflect Rings and Istory Falls would give me 2 - not attempting Leviathan without Coral Rings though. Neo will be a real challenge though....without Mighty Guard, multi target skills, Life2 or anything.....and I would need a LOT of Elixirs. I really hope that there is an easy way to make gil here.
Pretty easy playthrough; hardest fights so far were Seal Guardians and World 2 Exdeath.
Just finished Fork Tower myself. Everyone is level 35. Sent my Samurai and Dancer to fight Minotaur and my Ninja and Bard to face Omniscient. Minotaur took like two minutes to kill, but Omni took a while though; I had to sing Hero's Rime for a while before attacking him. Had no way to mute him so I had to resort to singing Romeo's Ballad then quickly attacking him while he was stopped.
About to go to Istory Falls now. Got 25 Elixirs so far for Neo.
Use Ninja and Dancer with maxed out Chicken Knife + 2 Reflect Rings. Dancer in front row. Ninja doesn't matter. Get a few high powered throwing weapons or Fuma Shurikens. Regular Shurikens will work too, it'll just might take longer. Get a Rainbow Dress for the Dancer, too.
I think your only hope is to wait until Omni reflects either Stop or Silence off of you and hopefully successfully hits him. If one of them successfully hit him, Throw the strongest thing you have and Dance ASAP for just that turn. Pray that you get Sword Dance. Or, you could replace Ninja with Monk, and hope for critical hits.