Well you can always shoot him from Ambush with a Crossbow.
I know it´s not fancy, but it tends to work (killed at least two Characters on this Level that Way.).
The Arch Magus has some AoE spells with Group target. Theses spells do like from 10 to 25 damage for Diameter duration. This is what confornts a group with magus just at most 8 years out of gauntlet..
The only chance I see other than said magus going into twlight is for the Order to get her.. If I remember the stealing vis from a magus can constitute take a mages power simular to destroying his gift. As it deprives him of his power (that being the raw magic if vis).
This is somewhere in the tribunal rulings and I do not have the book, could someone check on this.
Also, when the magus whiped out the sheep (vis sourse) in what way does the Order view the destruction of tangble priperty (which happened to have vis in it) as a possible crime. Such as we have farm anamals that are owned property by a magus and another magus comes along and notices some have vis in them and kills them for it. Can the injured magus make claim for the loss of tangable property..
Well considering we are agains a magus with arts in the 33 range at tops direst force is not a viable option at this time..
Thrumbar
All of what you have mentioned is a High Crime - depriving a magus of his ability to work magic. Something strikes me as odd about this... Why would an Archmagus want to steal a spring covenant's resources, and kill everyone?
Feh. Don't do direct, do sneaky. Read Sun Tzu, and take his advice - "The best formation is one that is unknown, the best plan is one that is unexpected." Do what he least expects, when he least expects it. Attack HIM on his home ground before he gets to you! 
Archers/Slingers, and Veil of Invisibility at Touch range. Take your 3 best woodsmen, make them invisible, and deploy them with orders to shoot after he passes them.
I posted a spell up in the grimoire section at L10 that would work wonders for this situation. It doesn't need to penetrate. Yes, you can't see him, but he can't see you either. Or hear you, for that matter.
And, if the putative covenant and gaming group as a whole survives this mess, ask for twice as much in return, plus punishments for any crimes he commits at tribunal.
Steve
Actually it isnt a high crime to take the resources of a coven that has wizard's war declared against it. You cant bring charges againt a mage for doing these things in a wizard's war. As to why kill young magi and take their resources the answer is simple .... She is Evil, greedy and they have something she wants.
As to attacking them before they attack you, this is difficult since the magi did NO research on the mage, never met her, never heard of her, never went to tribunal, dont know where she is or where her sanctum is. She is not a member of any coven as far as they know. They have ignored the order TOTALLY, this is the repayment for that disreguard. They dont even stop to listen to news from their redcap.
Btw the group has been 20 years out of gauntlet but some of the mages have made new apprentices because they made characters so crippled they couldnt play them enjoyably and found it easier to cop out than deal with the mess they made. If they run from this disaster also of their own making, their next setting will not be generously provided.
Great villians make for great stories and they have had it easy in the past. No more nice mr SG for them. Yes she will be a nightmare for them but they need to learn to deal with her or die.
Well even an Arch Mage has limitations. Unless this character has done nothing expect prepare itself for this specific fight (which would be to convenient- right?), it's likely that the Arch Magus doesn't have every protective spell, every tracking spell, every destructive spell.
I stand by my position that if a character shows to a fight there is a chance they can be killed. We've tossed out ideas on how that can be done.
Concerning ignoreing the Order. That can be changed. Wizard's War is called and does not begin immediately. Before it begins the characters have time to make amends for 20 years of ignorance. Run to a covenant, beg for help. As I mentioned before the characters need to get proactive and take matters into their own hands.
Also to be fair, in 20 years of game time the GM either in play or at the table has never suggested the players get involved in their community? Your mails have sound of giddy vengance to them. An "I told you so" sort of attitude. I've had characters dig themselves into incredibly deep holes and while I've had fun GMing these adventures I've never gone out of my way to school the players. I just hope this up coming adventure doesn't result in the campaign ending and animosity being held among people who are suppose to be friends.
I'd like to be the first to congratulate William on reaching the exalted status of "master" with his 250th post to this board. I hope you enjoy all of the secret powers and privledges that accompany your new title (no we can't tell you, they're secret).
well to give yall an idea where we at our little group consist of 4 players.
Player #1 Cleric
Started out a Cleric/exerist character. Was out Vim specialist but had a bad tendency to take the personal magic flaw so he can start off with higher lvl spells. A dispute on how wards worked and the events areoud this character he chose to abondon him and start another that was 15 age. He currently is playing that character now.
Player #2 Lecher
He started playing a somewhat selfserving lecherous player (oppisite of his real lifes personality). Give you the idea on how he played the character, at the start of the game my character almost died, instead of trying to help he invised and hid. He later took over the Cleric but made a new character when storyguide changed cleric to reflect Divine Book (could not cast hermetic spells or use any books to rais arts). His current character is almost dead by events surrounding the Evil Magus story (he went to assinate the evil magus but the place where she is holed up throws lighning bolts at anybody the come near uninvited).
Player 3 Flambo
He like me have our original characters from start (not gonna change unless death). He technically did not create his character, storyguide did that and he did not change anything, sorta like real life - women and work screws with his mind 
He has perty good virtues and flaws but has weak spont flaw so limits him mostly formulaic ( and he has no Pilum of Fire - for shame)
Player 4 (Me) The druid
My character is currently 17 Years out of Gauntlet (not 20 as we have only played the characters for 17 years in game time give or take a year). Currently my character in holed up in a secluded hiding place studying some labs we found. When he comes out the Evil Magus will send her familliar (Fae Dwarf) to most likely seize the 122 pawns of vis he has. Outcome is gonna be quite magical (short but painfull battle most likely).
Events in game started with us leaving the old covenhouse (we stoped playing our first game and made these characters when 5th ed was released because we though updating them would be more diffacult than making new ones.
At the time of our game start (about 1607 or there abouts) when we left the coven of our previous character (all 4th edition). The Flambo had diffucult underlings who promply tried to kill me.
Well we mad it to what could have been out first coven site, worked it a while but chose another a little farther away (one not likely to be on the road any major armies would use or near the place they would camp like the first one)..
We were in germany and with the 30 years war about to start relocating somewhere else was sorta looking good. The flamo wound up g=being a commander and having to ammass an army for the local Bishop which limited his time for Magus advancement to virtuall nothing, The Cleric became an assistant to the Bishop and suffered simular problems. As did out lecherous player which left me to be draged into all their problems.
Well we left germany rather than be cought betwen the Prdastants and Chathloc forces (not being liked by the general populaton of both sides - leave now of unite them long enough to kill us).
We are currently on Isle of Man (for info see Hermes Portal last 2 issues I think) having completed the placement of the baby dragons to keep the Isle from going back to the Fae. This is when the Evil Magus appears about a year or 2 after that was finnished. O the Flambo sorta spent a year of 2 in the Tower of London prisoneer for bribing the crown for his title. Hope the Storyguide dos not take offence to this post but wanted to fill in gaps. May have skiped some but wrote this in rush before work..
Thrumbar
One of the characters is sitting on a Queen and quarter of Vis and they can't beat an Arch Mage? Ok, these characters deserve to die. With a 122 pawns of vis let me count the ways I could wipe the floor with an Arch Mage.
1... 2... 3... Crunch! So that's what's at the center of an Arch Mage!
Erik Tyrrell wrote:
So is this a club of two? I'm not familiar with anyone else that has reached this much saught after position. And may ask a question concerning Master Tyrrell, with a clean 100 odd posts of head of just about everyone else, is there such thing as... Arch Magus? I mean with 340+ posts, doesn't this guy deserve a brownie or something? 
The problem is the one with the vis is working all the time and unless he was there the vis in unavilable to the other players. If ya not there to play your character he not in game that time.
That character went off to prepare for another encounter with the fae over A undead haunting this island off the Isle of Man and a powerfull fae cures placed on it when all this happened and only recently got caught up to the fall of 1624 when the Magus first attacked..
When he leaves the place he was studing 2 of 3 labs found hidden, something he planned before these events he have to port to the place where the Magus is and have a little chat with her and her Dwarf football ..
I will have to go and have a talk with her when they give me an Idea where she may be (they have idea seeing one was blasted near that area). Then me and her are going to have a long talk..
Thrumbar
and yes we perty lame to
if only vis added to dammage of spells and not just to casting totals ? 