There's probably a whole host of things you could do, but I'm going to recommend one of four options.
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Muto Vim (159, Core)
There are two ways you could use Muto Vim to your advantage, both are general levels (so, the higher the level of your spell, the higher the level your spells can effect).
A) "Significantly change a spell of less than the level + 1 magnitude of the Vim spell." Now, this can't change the Technique or Form, but it could change the magnitude of the spell you're trying to deflect in some way, or it could change the target (has to be a possible target for that spell).
You could use that guideline to design a spell which would, in turn, change the target of an incoming spell... to something that's NOT you. This would actually seem to be the method that's closest to what you want to do, essentially 'pushing' the spells out of the way.
B) "Totally change a spell of less than half the (level + 1 magnitute) of the Vim spell." This can change the technique and/or form, and doesn't even require requisites for what you're changing. Now the important thing here is that this spell can change the nature of the spell incoming, NOT the target.
You could use this guideline to, for example, change a creo-ignem fire spell incoming into water or air... it'll have to be something that still hits you, but not something that necessarily has to hurt. Either way, you'd want some kind of "change magic" magical focus to ensure you can easily reach the spell levels where you could impact a lot of different spells. "Change Magic" could probably sneak in as a Minor Magical Virtue, but some SGs may want to make it a major. It would greatly depend on how you fully develop the exact effects of the focus.
Pros (for both): It would be easier to create and cast these spells than the next suggestion (perdo vim). You probably won't need as many spells going with this method as the other methods on this list, for example, you could just create one spell that effects all other spells that are Voice/Mom/Ind lvl 30 and under.
Cons (for both): You'll need still need several spells. If any NPC or opponent had a weirdly crafted spell, you may not have a spell to effect it (ie if their spell had a Target: Group or Part, and your spell only effected spells with Target: Individual). You'd need to fast-cast your spell, which either means you spont it or you master a formuliac spell and give it the fast-cast mastery ability.
Note: You may or may not need to roll to detect the magic incoming; I'd rule that you could fast-cast cast whatever spell you wanted, and if that spell would work, it would change the spell in whatever way it was supposed to change it. If it wouldn't, it wouldn't work. You may still want to roll to try to detect what kind of spell it is incoming, only so you'd better know what to cast just in case, but you could still probably cast regardless.
2. Perdo Vim spell "Unrevelling the Fabric of (Form)" (161, Core)
Pros: This destroys magic. Whee! Cons: You'll realistically need 10 versions of this spell, if you want to be able to block all 10 different forms of magic. Additionally, you'll need fairly high-level spells for each of those forms. To make matters even more complicated, you'd need to roll to detect what kind of spell was incoming before fast-casting your own spell to destroy it, then fast-cast to destroy it (which, again, means you'd have to give it the fast-cast ability, or spont it).
Note: If you go this route, get thee a magical focus in Destroy Magic. It'll be tough to convince a Story Guide that such a magical focus isn't a Major Magical Focus, because it would apply to all 10 forms of hermetic magic, as well as items and maybe even magical creatures, etc. I may allow it as a Minor Magical Effect, because even though it casts a wide net, its focus is still narrow -- so a lot of the metaphorical fishies will get through -- but it'd be a tough sell.
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Ward Magic. This basically combines Rego with all the different kind of forms and automatically blocks specific magic (depending on the spells you use) from hitting you. The flavor of your character (his sigil) could have the (free) cosmetic effect of making the magic your Ward blocks appear to "push off" to the side, going out of the way, like you seem to want. Again, you'd probably want a magical focus for wards if you went this route.
Pros: This blocks the magic, so you don't have to worry about it, so long as your ward spells are high enough levels. It requires no fast-cast magic, or any action on your part, beyond casting the spell. Some of these spells can last a very long time (Circles can last for a long time, or you could make it a Personal spell with a Sun duration).
Cons: You'd need to have a fair number of different Ward spells, many of which would be fairly high level. Most Story Guides will still make you roll to make sure your wards "penetrate" the spells (ie if your spell is higher than theirs, it's still not necessarily a block), so you still need decent penetration with your ward spells. The fact that you need penetration against other Magi for your wards is actually a big deal.
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Dimacatio/Fast-cast magic. If you have the Societas house book, I highly, highly suggest reading the section on the Dimacatio (21, HoH:S), and you'll also have to read the rules on Fast Casting (83, Core). Basically, using this technique, you'd fast cast magic that would be used to block other, incoming magic. I find this a highly realistic way to think of a true Wizard's Duel. So, when that ebil Flambeau wizard launches a huge fireball at you, you fast-cast a giant spike of ice shooting from the ground to block it.
Note: For your spell to 'block' the incoming spell, you'd need to have a an appropriate kind of spell that's at least half the level of the one coming at you (The book says "appropriate" because some spells just aren't going to block an incoming spell, no matter what level the spell is that you cast. A small, but high level, gust of wind isn't going to block a dozen magical arrows heading your way, but a tornado would. Your SG will ultimately be the one to decide what "appropriate" means, so chat with him before you decide to go this route and make sure your idea of "appropriate" is close to what his is, or it's going to ruin the fun for you. On a personal level, I think most spells will block incoming spells so long as the effect you create is high enough, so I interpret "appropriate" pretty loosely... but that's just me.)
Pro: You won't need any special kind of magical focus to go in this direction, so you could further develop your character to be good at other things. Only having to create effects that are half the level of the incoming effect allows you to block high level spells with mid level spells, or block mid level spells with low level spells. This is good. LOL. Most importantly, this is a FUN way to play the game!
Con: There isn't any obvious kind of magical focus (that said, anything that helps with sponting could be very useful here, like Diedne magic). If you want to be able to use your Formulaic spells, you'd need to Master each spell you'd plan to use this way, giving them the fast-cast effect (so you could fast-cast them, using fast-cast rules). You may also want to spend some virtue points to make your fast casting more effective.
Note: I have no idea which would be the most effective route. My character has a magical focus in Wards and I find it generally useful, though I wish it were a bit more powerful against magical effects (ie, that my wards didn't have to penetrate it). Some Story Guides don't make Wards need to penetrate, making them much more powerful. Going Wards has the added bonus of being able to Ward against mundate dangers -- like iron and wood, for weapons, or even a spell like Ward: Human.
I think you'd probably have the easiest time landing the Muto Vim spells, so that may want to be the route you go, but the Dimacatio route would also be very effective -- and fun to roleplay (it makes me think of the big wizard duel scene in the Merlin miniseries, where Merlin faces off with Maub at the end -- youtube that, it's a fun scene!). You could consider play testing each of these ways and deciding what works best and what's most fun to play for you.
