MY STRATEGY OF BEATING LAMIA WITH TWO PEOPLE
I use a Poison Unit, a Sleep Ward Unit, a DPS, and a Healer w/ Time Control.
Less units make the dungeon easier, and it never takes more than two turns to get the Eidolon you need.
One person takes Xerxes/Physical Eidolon, and the other takes Chaos.
The first three floors are easy enough to where there needs no guide.
However, on Floor 3, there does need to be some set up.
On the last turn before the last mob dies on Floor 3, I position my Sleep Ward Unit in B2, and my Poison Unit in B4. The Poison Unit will be asleep and demoralized, but your Sleep Ward Unit will be unaffected. The other two units can be wherever, as long as they are away from the middle in case of being locked in.
If the first person to move on Floor 4 has Chaos, wait till Turn 3 to use it, if not, then use it on Turn 2.
Proceed to pincer with the Poison Unit and the DPS Unit on Nullify Healing/Breath turns and avoid Lamia on Panacea/Ram turns.
When she gets low, make sure you have the summon point charged up, so when she summons the Perentie Army, it makes it easy to get the physical eidolon summoned.
The next step is to pincer her on just non-Panacea turns (since she will just go to the Panacea/Ram then Ram cycle)
If there is a Perentie, try and poison Lamia using it instead of pincering Lamia herself to avoid damage.
You then win, and Celebrate the Mat Drop or Cry for No Drop/Ore Drops.
Ca a quand même l'air facile. A'misandra qui peut être utile (Deathward chain).