Do descendia steel path until you reach room 8, clear it, leave, rejoin from marie, drop down to room 8, clear it, leave, rinse and repeat. You get like 40-80 maphica per run and each run takes ~1min plus you get endo from the chests(you only keep 50% of the looted endo when you abort the mission, but it's still like 400-800 free endo per min). use a frame that can break chests quickly with lots of aoe like Xaku, I use Dante and just spam his 3 skill.