Five-starred Gigantuar with a lucky Random:Instant Chain. I would recommend not attempting this until you have three characters over 10,000 HP, for obvious reasons. Daze, as you may know, is the key to this fight.
Also five-starred the two Raktavijas. I found the key to the latter was to invest in upgrading six Witch's Bracelets to level 10, which gave all three of my party members about 43% magic resistance, which made the difference, and therefore was worth the resources. Genji Glove - Got!
Attacus the Soulless is next on my list.