I'm a loser baby, so why don't you kill me?
*This is a low level challenge run of SMT: Digital Devil Saga. There's only one rule this time round - no gaining EXP outside of forced encounters*
The first phase is not too dangerous, just wait for Sera to stop being dumb and tell you where he is. Buffs are retained between the 2 phases, so take the chance to stack em now while he's less threatening (the second form has De- spells but doesn't seem to use them on 2 stacks)
Keep a force repel shield up at all times during phase 2, because Infinite Wind hurts. He always follows up Hunger Wave with Infinite Wind, even if you get a turn between them. He also always opens with Hunger Wave and uses it again at the midpoint. So the key is really to let him kill himself. Debuff him a little in case of Megidolas (double Megidola is really the most dangerous thing he can do) and focus on healing and keeping that force shield up above everything else. With 2 Force Repel casters you should usually have someone available to cast it (unless Hunger Wave hits your entire party AND Sera is dumb - not as unlikely as you'd hope) but in a pinch you can always throw a Magic Mirror.
Heat learns Void Phys in this one, which will be useful in the Karma Temple and beyond.