suggested Virtues?

Can any of you gronards out there suggest some obvious and not so obvious virtues that would benifit a Mercere Magus focused on spontaneous magic? For forms, he is focusing on Vim ("meta-magic"). For techniques, he likes, in this order, Perdo, Rego, and Muto. The magi is an apprentice who is just about to pass his gauntlet.

Secondarily, he will want to be good at Original Research, specifically but not exclusively in the areas described above.

The player is an experienced rpg-er, but new to ArM5. He submitted a character that doesn't exactly work, but this is what he is trying to make, and I'd like to give him some guidance on how to make this character more effective, but I'm still getting up to speed myself so my advice is limited. The player has not yet had an opportunity to read the Mercer chapter, so I don't know if he'll be a legitimate decendent of Mercere or illegitmate, Mercurian, Mutantes, so suggestions in that area welcomed as well.

Thanks in advance...

CHeck the munchkin character thread. There were some really cool ideas there for (Maxed out) spont specialists. I specially liked the ritualistic dance sponter.

Xavi

If he's planning on focussing on Vim magic, consider Deft Form (Vim). Being able to cast without words or gestures without penalty is a massive bonus for a spontaneous caster.

Stay away from mercurian magic, but do consider the virtue that makes ceremonial casting 2 minutes instead of 15 per magnitude. A minor (or major?) magic focus on spell boost spells would be funny as well, to boost the effective magnitude of the spont spells.

Another option is the magic focus sketched above, and flexible formulaic, you have a few spells formulaic, and make of them what you wish. Not really spontaneous, but very versatile.

Special Circumstances and Cyclic Magic is something to consider. Together giving +3/+2(1) to spontaneous. It´s not a huge amount, but it doesn´t matter what Arts are being used something which can make them quite useful.
Maybe Puissant+Affinity for Vim, if he really wants that as a serious focus?