I have a vested interest in this because I'm one of the other PCs in this game and I need said magician to provide magical overwatch.
The great thing about Prime Runner is that you can get a lot of nuyen at Resource E, which frees up some priorities. That will make being an elf magician a lot easier. Of course, foci will eat up Resources E pretty quickly too. Remember that we get a free fake SIN from the GM's chargen rules so that will save you ten grand right there.
We have combat, B&E, and social skills well-covered by the group, so don't worry about those.
Here's my wishlist for things for the magician to cover:
1) Spellcasting
2) Counterspelling
3) Summoning
4) Assensing
You'll of course need Sneaking and Perception too but don't try to cram too much more in or you'll find yourself stretched too thinly.
For spells, you'll start with 10 if you take Magic A and it might be worth it to pick up 2 extra spells if you can find the karma for it. There are several threads on the forum for people looking for advice if you want to do some research. I would recommend these no matter what:
- one direct damage spell (stunbolt, manabolt, etc.)
- one AOE indirect damage spell (lightning ball, fireball, etc.)
- Heal
After that, other good options include Levitate, Magic Fingers, Physical Mask, Trid Phantasm, and/or Improved Invisibility. For your own survivability, Increase Reflexes, Increase Intuition, and Combat Sense are all good choices, probably in that order. Alternatively, you can get Detox and go the pharmaceutical route like Jack_Spade suggests. Also very viable.
Depending on your background and whether the character is a dedicated vampire hunter or just a shadowrunner who needed the work, vampire-specific spells like Sunbeam (from Shadow Spells) and Detect Vampire could be fun and highly useful.
A rating 3 Power Focus is great if you can swing it, but if it's too much then rating 2 is also very good. You can have up to 6 rating points of foci without risking foci addiction (presuming your Magic rating is 6), so I would try to get a sustaining focus for the remainder of what you have available. So either Power 3 + Sustaining 3 (24 karma total, ¥66,000) or Power 2 + Sustaining 4 (20 karma, ¥52,000).
Mentor spirits are a good value. Focused Concentration is great too if you don't go the drug route, but I know things are going to get tight. Remember that we start with 35 karma for Prime Runner. Let's say you take 25 karma of negative qualities too, which means 60 karma total to spend:
Foci: 24 karma
Mentor Spirit: 5 karma
2 extra spells: 10 karma
Focus Concentration IV: 16 karma
That's 55ish karma, leaving a handful for conversion to nuyen or a couple rating 1 skills. I would probably skip Witness My Hate unless you decide to go heavy into the Direct damage spells (which is a perfectly viable approach, especially for dodgy bastards like vampires). If you go Race D for Elf, you might want to find 10 karma for an extra point of Edge. Either pick up some more negative qualities (since Prime Runner lets you pile on 35 karma worth) or start trimming back here and there.