..You didn't? o.o; And you never used a UA combo? How did you survive o.o;
I dunno. Prism Stars is really pwetty. ^^
To talk to Abyssion, you have to have one of the Devil's Arms, preferably Colette's Evil Eye (you can get the one in Triet first too though, I think it belongs to Zelos or Kratos).
To get the Evil Eye, after you destroy that Bacura thingamajig in the mines, go to the remains and examine them. And... It's there. o.0;
To get the one that belongs to Zelos/Kratos, go to Triet in Sylvarant. Talk to the people there (the one by the Katz thing and some guy by the fortune teller tent I think, but just talk to everyone), and you'll hear about some dude finding a cursed sword in some ruins and getting eaten by a sand monster. Leave Triet, and run around, and you'll find a ring of light that looks like a skit point. It's really a monster, but it isn't hard. After you beat it, Lloyd finds the Devil's Arm.
After that, Abyssion should be hanging out in the front of Flanior. Like, in front of that place that's closed. And he has... blue hair I think. Yeah. He isn't hard to miss really.
You have to get all the Devil's Arms before you fight him though, then he'll tell you to go to the Temple of Darkness. And one of them is in Welgaia, so if you miss it it'll be a looooong time before you go back.
Most people recommend level 75, and if you're below it then use an All Divide.
I don't think Abyssion is as hard as people made him out to be, but the battle takes forever. And I mean FOREVER, especially with an All Divide. -_-