What about the achievement Black Magic? You can get it easily. Exactly because of the combo, Clemons is very weak when he cannot use moves that require focus. When he casts uknown condition thrice in a row use mind freeze on him and watch him healing you. Just keep him flash or mind frozen all the time.
Yosuke: This battle isn't hard, just extremely long. There is no way to penetrate his Immortal Flame buff so you're just going to have to put on some music and wait it out for 99 turns. Remember to keep the combo on him though because if he attacks you with focus, you're done for. Once the buff is off you attack him like any other battle and since he doesn't re-cast the buff the battle is yours.
Why would you have to wait that long? He is very vulnerable to damage over time so use Hypothermia on him. You may have to re-spec but there shouldn't be a problem. Worst case scenario you switch to hot hydraulic to cast wreck, decimate and lasting pain.
Versu the Corrupter: Again quite a difficult battle. Do not attack the orbs! Because if one orb gets killed then she turns into her Corrupter form and then must re-do the battle. Just keep attacking her and let your team mates waste their time on the orbs. Remember to use Shatter and you should win. And then CONGRATULATIONS! You have achieved Over the Ashes and completed the game!
I don't know, since you are the tank, you should be able to last it. I just keep killing the orb that heals her (with the buff perfect design). You must let the other live because it casts a buff on the corrupter that severely contains her power. You may have to use subversion on that orb in order to make it heal itself (due to the "flawed design" it loses health every turn).
