Just out of curiosity, I decided to scribble out a few numbers regarding the MP efficiency of grinding this dungeon over rolling in the REM.
Assuming that:
- They don't decide to nerf Master drops in the future, ie: drops are 100% per floor
- the Predra drop rate is 1 in 3 on floor 2
- 1 REM roll is worth 5000 mp (lol)
With that out of the way,
33% of the time, you would get 1 Predra and 2 baby Predras for 700mp
66% of the time, you would get 3 baby Predras for 300mp
So on average, you should be getting (0.33)*700mp + (0.66)*300mp ≈ 433mp per run on master
For griding this dungeon for MP comparable to a 6* REM roll to be worth it,
5000mp/433mp ≈ 11.5 runs
11.5runs/5 stones ≈ 2.3 runs/stone, or:
≥ 3 runs per stone
which is also:
≥ 150 stamina per stone
tldr; grinding this dungeon for MP on master difficulty is efficient and comparable to a 6* REM roll (5000mp) starting at 3 runs per stone, or 150 stamina per stone, minimum.
(Rank 267 hits 150 stamina)
Which shouldn't be a problem for most of the people here, I'd imagine. At 131 stamina, I wasn't being MP efficient with my stone usage, in other words.
If you must know, if your luck is utter crap and the game hates you and will only drop baby predras for you, then it becomes efficient at 4 runs/stone or 200 stamina/stone minimum.