Shouldn't stoneskin and mirror image take care of that?
But can't go wrong with true sight either.

Is this topic too old?

Well, anyway, I for one remember my melee warrior heavy days, when enemy mages would suddenly disappear, and then reappear OUTSIDE their spell protections. I'd whack away, have them die, only to reappear again inside their protections (in other words, I had no clue how to handle a Mislead spell.)

Then there are the times that Aerie (my only spellcaster) just would not Breach their Protection From Charname spells so that I could slice away in the fair contest of Berserker vs mage. :D Ah, Somewhat Invisible still counts as Invisible.

Melee heavy parties will learn to appriciate Keldorn right quick. :D

Also, I found that, in my last playthrough as a mage, that I didn't have the blasting power to ignore other mages' defences for quite a while. I had five (of six) party members who COULD cast True Sight; and each of them had at least one memorized at all times. :D

Stoneskin is great vs thieves (Aerie must have been SO glad to have me learn that; now she doesn't die everytime a theif looks at my party funny.) But just yesterday, I did the Planar Prision quest.

Little Miss "All Backstabbers target my feeble 40 hitpoints please" had stoneskin up; and yep, the invisible theif went for her. And knocked her flat out. As if she had been punched to 1 hp. She was out for a good few minutes. I was mageless against that Yuan - Ti; who can be annoying if you ignore it too long. :D

Darn Pixie Prick; never works for me. :D

If you're not soloing, you could always use the thieve's DI.

Couldn't you use Detect Illusions even if you WERE soloing? That is, provided your character was at least part thief?

Well, yes, but not all Solo games are part thief ;)

Especially solo sorcerors, who are the only ones that have to make the choice of whether to learn True Sight or not.