That was very helpful, thanks guys ... Does: Luci, Enchinda, Vampire, RK, Siren, Luci friend sound about right?
These guys are all talking Mythical. Do Legendary. You'll breeze through it with your team (without Enchidna).
SOD Luci lead, RK, Siren, RK, Vamp, SOD Luci friend. Get another RK if you can.
Rundown:
Round 1:
Blazing Ice Ogre (BIO)
Flaming Armor Ogre (FAO)
BIO will lock someone down for 10 turns, pray it's not a Luci. If it is, just tough it out and heal only exactly what you need to heal while trying to keep spare hearts on the board. FAO will bind Siren for ~4 turns. Focus fire down one of them (doesn't matter which, though my team had two water monsters, so I went against BIO first since FAO takes 1/2 damage once he's at 50%), then do the other. DO NOT DO BOTH. Damage spikes from both once they get below 35% (or 50%, I can't remember). Make sure this takes at least 30 rounds (it will, because you're slow grinding and won't have as much ATK to power through).
Round 2: Sacred Flame Dragon, Formula (Fuckit).
Stall to build up hearts and flame orbs. Nuke Fuckit with a Lucibomb.
Round 3: Green Flame Ifirit
44 hp... stay as full as possible. Should be 6 matches of blue and black to kill. If you can stall to recharge, go ahead, otherwise, make sure at least one lucibomb is up.
Round 4: War Diety Dark Minerva (DMin)
510k ish hp. Stay above 50% health yourself, get her to 60% health, lucibomb her to death. No worries of bind, mass attack, or anything else. She hits for 6K a round (and will preempt with a hit too).
Round 5: Awoken Hera-Ur (Ur)
Ur will bind Siren for 10 turns immediately. Second turn will be status shield. Hope you saved some hearts. Grind away carefully. Ur hits for 14k normally (10k regular attack that rarely fires). Just keep grinding away slowly. It's going to be perilous and tedious. You'll burn stones because you'll be going to slow to avoid being fucked by random chance. Once she hits you for 18k (that means she dropped to 50%) you have a chance to really gamble.
I always did this: Luci-nuke, Siren-heartmake, match for some vandamage (3k from each monster), Lucinuke for the win. This works because you drop the luci nuke to bring her to 26%/27%, heart match/nuke to sub 25%, free round for her to charge her killshot, then you kill her with your last nuke.
I actually try to chain run this dungeon (as stamina allows) because it was so easy on Legendary for me. I should probably try out Mythical, but fuck that.
My team is in my link (SOD, BlOdin, HeraIs, Siren, RK or DD Hades, SOD ally) and is pretty beefy at 65k hp. Add Lang on here, his SOD is bullshit-level stats and should help your run.