Mmh it is not so easy...
The grogs die... but what if they are covered with parma by the supporting magi, which are far from the battlefield, and have a bunch of sight spells, with finesse and stuffs to kill the enemies. With eyes of the eagle, you may be 2 km away and still get sight on the event.
Your magus take weapons... unless they are talisman, they will be soon destroyed by any kind of magic : a fire ball on you may not touch you, but if the enemy is not aiming you but your sword...
If those are talisman, they are arcane connection to you, and any wound done by an item is an arcane connection to that item. Easy to use the killed magi to have an arcane connection to you.
If you are fighting, the supporting imaginems and mentem magi will play their strength and let the weaker magi attack the not weaker.
Yes you have a wizard's war with them. But did you have a wizard's war with your ally? No? How will you prevent him to stabbing you? Too late, the time that you think about it, an enemy sneaked up on you and stabbed you with his ice dagger. Real ice man, sorry, your ward against metal/stone/corpus failed as your parma.
You are casting your big spells to the grogs? but the grogs are illusions. The real grogs are attacking your campbase while some magi are playing with you.
You used 30 pawns of vis to penetrate their aegis? How unlucky! They cast three aegis the day they received your letter.
You gathered the vis for your casting? Too bad, their fastcaster magi just teleported your vis in their aegis. Thanks for the supply!
You are doing your parma? What are those earth shaking? An earthquake, you must run or die! Oups, who is that man following you? Oh yes, an enemy. OUps, where is your parma? Dead.
You are doing your parma in the forest? Bad luck, the forest went on fire. Yes, a magical fire. Yes, the forest is a a boundary. Oups.
You see those 21 "enemy target"? One is real. Which one? Bad guess. dead
You see those 2 "enemy target"? Which one is real? This one? bad luck. That was the species of your friend whose parma imaginem was lacking... Yes, you just killed him. Oh by the way, while you did that you have been stabbed.
Wait, you don't see me because of the fog? An impenetrable one? Quickly, an InAu. What? you never learned that spell? Will you really tire yourself?
Oh, a balista bolt. No problem I can manage that bolt! Bad luck, it was not a bolt of metal, only a reagent of acid covered by a momentary muto imaginem spell. Bad luck.
The earth is shaking! "it's nothing you say, we have parma"? Yes, sure. But however, it was a perdo terram on the subterannean eart. Talk about disorganisation! Wait, what are those erupting rocks? Yes. Surprise? A little MuIm to seem to be rock while a earthquake. dead
"Our aegis is powerful!" "you are right" ReTe big rocks x10. Let those drops.Oh, by the way, yes, they are MuTe(Au) while we move them above your head; too bad you only had InIm to see through our illusions. "TIMMMBER" dead
"You did take supplies I hope?" "yes, we bought wine in summer" "oh, I thought about others. I had a bowel disease invented in that one" dead
And so forth, and so forth.