Invis is useless in its current form against anyone who is A) Not lazy (this is what gets me killed) B) Not a newbie and C) Not a pre-25 rager. Let other melee classes share in the pain. Bump up hieghtened awareness and other detect invis skills to 25, Make invis like assassin hide in its usability, Make all potions/pills level 25 or higher (I'd say 35) allow for scrolls/talismans at say 25-30. Basically give every mage the opportunity to pick their fights and I think you'd see a lot more low-midbie mages trying to throw down. By making it so they can't just invis once they've gotten in a fight, you also give melee classes a chance for revenge. I'd probably also move recall and teleport up in the level you can get them as a potion/pill and make scrolls and talismans lower for recall.

Basically, allow low level mages the ability to move about more freely than their melee counterparts, but at the cost of a scroll or talisman vs a potion, meaning they can whittle down more easily, and allow them to invis and have that mean something.

Might be too much, but I'd sure abuse the crap out of it.