For those who's mags are Lv100, but did not get a rare mag(I posted a list earlier), or just want to use another kind of mag, here is the list of Mag Cell mags:
http://www.pso-world.com/sections.php?op=viewarticle&artid=659
http://www.pso-world.com/sections.php?op=viewarticle&artid=2343 (note that Geung-si, Moro, Pioneer 2 are unobtainable on SCHTHACK, and Puyo and GG are hard to come by).
http://www.pso-world.com/sections.php?op=viewarticle&artid=1016
Reference guide for what each mag looks like.
For the record, the following Mags have all invincibility as their triggers(some of the regular 50+s have all invin, but their trigger activation rate is low):
Soniti
Nidra
Sato
Tellusis
Agastya and Gael Giel almost have all invin, though Aga has HP recover(useless at high levels for 1/10 HP), and GG has S/D for boss entry(not a big problem, the boss cutscene usually wastes the invin anyway).
How to easily obtain Cell of Mag 502(Soniti):
http://psowiki.net/wiki/AOL_CUP_-Sunset_Base-
Most other cells are obtained in events, though you get one Soniti free per character.
Dragon Scale(Tellusis) can be found from beating Shambertain(blue version of Ep4 boss) on Point of Disaster.