The thing with BG2 mages is that, in the vanilla game (without SCS), they are all pretty consistent in their tricks. You can counter most of the bad things they can do to you with just a few spells, and it isn't that hard to learn, really. It's only frustrating when you don't have the basic knowledge.
- Almost every mage is going to cast Horror and try to cause mass panic in your party. I keep the cleric spell Remove Fear active at all times when my party is in danger, because it prevents the Horror spell from working. If I do not have Remove Fear already cast for some reason, it is the first thing I have my cleric cast on sight of a mage.
-Almost every mage is going to cast at least one and possibly several devastating mind altering spells like Confusion, Chaos, Domination and/or Dire Charm. The cleric spell Chaotic Commands protects against all of them. I keep it active on all party members whenever the party is in danger. In a full six-member party, I like to have two clerics so I can keep everybody covered.
-Many mages and clerics are going to try direct save-or-die spells like Finger of Death and Disintegrate. The cleric spell Death Ward protects against all of them. I keep it active at all times during danger, at least on Charname.
-The cleric spell Protection from Evil 10' adds a significant bonus to saving throws, increasing the chances of only half damage if the mage gets down to his or her big damage spells. Again, keep it active during all times of danger.
-Before going to their mind-altering and then big damage spells, mages like to cast a series of protection spells that make themselves very hard to hit. Many of them are programmed with a Contingency that lets them cast these protections instantly upon going hostile, or to be already cast when you find them. The spell Breach very reliably removes almost all physical protections, so your fighters can hit the mages and make short work of them. Breach is the first spell I have my mage cast upon sight of a protected mage. If there is more than one mage, getting a Breach cast on each of them is a priority action. That's why it can be a good idea to have more than one mage in your own party.
-In addition to the magical physical protections, mages like to use Mirror Image, Improved Invisibility, Dimension Door, Mislead, and Project Image. These illusion spells not only make the mage hard or impossible to hit, Improved Invisibility will make him or her untargetable by spells, including Breach. So, casting the counterspell True Sight is a priority action for my cleric in a mage battle, if I don't have Keldorn. I prefer to have Keldorn so he can cast True Sight on the first round. If my cleric has to do it, it may be necessary to cast it before the mage(s) can Breach.
-If the mage is surrounded by a silver glow at the base of his or her feet, Spell Turning is cast, which will reflect any lower level offensive spells back against you. If there is a blue globe, the mage has cast either a Major or Minor Globe of Invulnerability and is immune to spells of possibly up to fifth level and lower. If you want to cast offensive spells at an enemy mage, you have to start learning to use the more complicated counterspells like Secret Word and Pierce Magic. I find this completely unnecessary in the vanilla game. Mages fall easily to melee once their physical protections and illusions are dispelled.
-The one exception to the above is dragons, who are very hard to bring down in melee even with their magical protections dispelled. Against dragons, you need to cast several Lower Resistance spells, at least two. Three or four are better. Then, you can bring them down with simple offensive spells like Magic Missiles.
tl;dr: You can win most BG2 mage fights with just a handful of easy to remember spells. Remove Fear, Protection from Evil 10', Chaotic Commands, Death Ward, Breach, True Sight. Add in an item that gives Freedom so you won't get stuck in a Web, Paralyzed, or Held, and you're good to go through 99 percent of all the magic-heavy battles.
way.
