I've been trying it out, and I can't seem to get that Pixie to run out of MP before using Recarmdra. I can't tell if I'm just getting unlucky or if I'm doing something wrong. I can't find a full description of this strategy anywhere, just vague descriptions, so can someone tell me how this is supposed to go?
You need to keep spamming a debuff spell ("Debilitate" is the best option) so that she uses lots of "Dekunda" I believe. I don't think she'll run out of MP even if you're "lucky" enough to have her cast "Megidolaon" 29 times in a row.
Basically, the "Red Star Strategy" involves "locking" the battle when both Pixie and Arahabaki are out. You need one character to have a debuff spell (Again, Debilitate works best because it debuffs everything), and another with a buff spell (Either "Sukukaja" or "Rakukaja" will be most useful... I'm more of a fan of Sukukaja for the fight), and your main source of damage is going to be the spell "Last Word" (Mega almighty damage, single enemy).
How this works is that when the demons cast either "Dekunda" (Pixie) or "Dekaja" (Arahabaki), it doesn't count as a turn for them, so they won't use "Recarmdra" after 30 turns of battle. Your purpose is to stall the battle long enough while using buffs and debuffs until Pixie runs out of MP, while you keep healing yourself and maintain MP (Salvation and Debilitate use quite a bit of MP).
The result: Pixie now spends the rest of the battle casting "Dekunda", but without MP, nothing happens. This gives you a chance to fully debilitate the Demi-Fiend, making him far less dangerous. As an added bonus, once the Demi-Fiend reaches 50% of his HP, Pixie will attempt to cast "Mediarahan" (A scripted event that happens the first time he gets to 9000 HP), which won't work. If you keep your buff active, the only enemy who'll attack you is now the Demi-Fiend himself... Who is now a joke, because he's fully debilitated, so any damage he DOES manage to hit your party with (Assuming he doesn't miss) will be much lower.
Currently playing: Shin Megami Tensei: Devil Summoner - Raidou Kuzunoha vs. the Soulless Army (PS2), Dissidia: Final Fantasy (PSP)
Thanks. I was finally able to beat him. The problem was, I didn't realize that Dekaja/Dekunda didn't count as a turn. The one description I managed to find of this strategy made it sound like Pixie was going to explode after 30 turns no matter what and I had to drain her MP in that amount of time. To further confuse the issue, the first couple of times I tried it, Pixie exploded after about 30 turns anyway. I suppose I got unlucky with the criticals.