[LF][Question] Best light jewel farming?

Hi,

I am in dire need of light jewels and as we have today 10x egg drop on top of sakuya invade, I was planning on do some serious farming. But I have some questions:

First, I do not have ALB. I mostly play ABastet/Sumire, but have good ADQXQ and APandora teams.

1- Do invades happen in descended challenge? Zeus is there and although it is only 5 battles, I could farm it with a Pandora team without paying much attention. (In addition, I am currently also at 0 mystic mask, so getting some could help).

2- The most efficient (Stam/battles wise) would be mephisto, right?

3- Should I instead farm Rare Monster Invasion? with 1.5% is it a guaranteed jewel drop?

Thanks for your help, and if anyone wants to farm in like 3-4 from now, send me a PM and we can set up a coop room.