I'm going to refine this a little bit.
The hunter that feeds the mag at 50 has to be Viridia, skyly, purple, Red, or yellow. You won't get twins otherwise.
The plan given also assumes that a ranger feeds the mag at 10.
Once you use the mag cell on the mag, feed the agaysta antidotes until you have 42 DEX.
After that feed the mag dimates to 200.
Alternative plan because everybody and their mother uses an estilla, pilla, and twins mag. These will be slower feeds, but they should end up being slightly better than the above plan because it will have a unique PB. The feeds are also only marginally slower (don't feel like doing the math right now, but it should be less than an hour difference).
Do the first evolution as a force if you want the resta pb. Do the first evolution as a hunter if you want the dragon pb.
Feed the mag antidotes up until you can use the mag cell on it.
Once it's an agaysta, use antidotes for DEX and dimates for POW.
For general mag tips, this page will be your best friend (along with google for when mag cells are usable).
http://www.pso-world.com/sections.php?section=Mags&op=viewtopsection
The most important pages there are Ranger/Force/Hunter mag evolution chart and the feeding charts. Evolution chart is for photon blast planning. Feeding charts let you know what you should feed the mags.
Important things to note about mags:
+100 is a level
I think this is a glitch here, but the second evolution (ashinvau, mitra, marutah, etc.) ignore the current feeders class. If you have a varuna, you will always get rudra, marutah, or vayu. If you have a Kalki, you will always get surya, mitra, or tapas.
When you're switching characters for specific PBs, keep feeding the mag 1 past the evolution level to avoid an annoying visual glitch.
In the pso world evolution chart the left most column is primary attribute and the rightmost column is secondary attribute. For example, you will get a Bhirava if your mag has POW>MIND>DEX at evolution level when fed by a type A ranger. You'll get a Varaha if the mag has MIND>POW>DEX at evolution level when fed by a type A ranger.
Third evolution mags evolve every 5 levels. Mags stop evolving once they turn rare.
Edit: I should have read fyrewolf's post before I started typing. I do disagree on the PB point though. PBs are almost exclusively used for superpowered S/D, so having a unique PB is better than having the best damage PBs. This is also why I like the resta PB the best. It may be a very minor thing, but a free resta+chain is marginally better than chain alone. This isn't true when you have a dark flow user on the team, but you can just be the twins(or pilla) guy whenever that happens