In my opinion, the game's UI does a poor job of explaining limitations to you. There is probably some rule that you don't satisfy, and the button is locked out accordingly, but it doesn't tell you what rule you failed. Could you post a screenshot of the character record page for the affected fighter, so that we can see your alignment, your attributes, etc.? Unequip any attribute-modifying items before grabbing the screenshot, since attribute requirements are judged based on your natural scores, ignoring any equipment-based modifiers.

Good idea.

It's true that some of the most rewarding moments in older games, like this one, are when one actually works out how to do something in the game. ;)

Here is a screenshot of my vanilla human fighter, just after the game begins, without any attribute-changing gear. As far as I can tell, there should be no impediment to dual-classing into either a rogue or arcane class, since both those attributes (physical: dexterity and mental: intelligence) are above the minimum for those classes. (I'll peruse the manual, as well, to see if there are any clues to solve this enigmatic puzzle.)

To dual-class in 2e (and probably 1e), you need:
* 15 in the prime requisite of the class you come from.
* 17 in the prime requisite of the class you want to change to.

Your fighter has only 14 Strength (which is the fighter's prime requisite), so she is unable to dual-class.

(Unfortunately, you might not be able to fix this; I think there might be a one-time strength boost in Watcher's Keep, but that's probably too late. You're going to start over. Blame the dual-classing rules and the fact that stats don't improve at level up in this game.)

Aha! You are correct. (As I noted earlier, I forgotten more than I remember about a lot of the particulars of these games.)

Take a gold star from the kitty, or an internet cookie, or whatever the clever kids are doing these days.

My thanks. (That could have distracted me for a while. As it happens, I'm really enjoying my Monk. :)

(I could have moved two points from Charisma, since there is no difference between a rank of 8 and 12, since the character needs a 13 to gain +1 reaction.)

It's always bothered me how AD&D is like that with ability scores.

(I also don't like the combination of dual class stat requirements and the lack of stat growth; actually I don't like the lack of stat growth at all, because it forces the player to make a permanent decision before the player is familiar enough with the game to make an informed decision.)

They usually work-around that with gifts: tomes were the official title of these books that granted a +1 in a particular stat. Ugly, but effective.

One of the crueler consequences with constitution was the chance to fail a resurrection attempt, and the penalty of a rank upon successful revivification. (I still check my CON after a resurrection, even now. Usually I load a save and redo the battle to avoid even the memory of death. :)

That's one mechanic that I dislike, and that I'm glad that CRPGs have largely abandoned. I much prefer it when resurrection is easy and doesn't risk permanent consequences.

Now, if only they would abandon the mechanic where dead characters fail to get XP, even if they were alive for most of the battle...

(Dragon Quest 9 allows characters who die during battle to get XP, but it also has the mechanic where higher level characters get a bigger share of the XP, which is backwards of what the mechanic should be. SaGa Frontier 2 allows dead characters to get stat/skill gains after battle. Some games, like Wizardry 8 and the SaGa 3 remake, allow stat or skill gains to occur during battle (though, for Wizardry 8, only skills, and death still prevents XP gain).)

If you are willing to cheat a bit to fix this, you could use the game's debug console to cheat in a Tome of +1 Strength (item code: BOOK04). Though no such books are found in Baldur's Gate 2, I think you can still create one. Many BG1 items are still valid in BG2 even if they cannot be found.

This will leave you with one stat point more than otherwise, but your current total is 89 across all stats. This is high, but I have sometimes rolled higher, so a score of 90 is not unreasonable.

From spells, I'd avoid any elementals with a mage.
Go with a druid to call elemental princes. Amongst those, Earth is the thoughest.

From charges, fire has a limited charges, while others come with daily uses. The Air rod is particluarly easy to get early, so I tend to cast those regularly, and they are fine.

The problem with fire dmg is, eventualy everything becomes immun to that element.

Thanks. I was trying not to (continue to) derail this topic. (I seem to enjoy creating characters more than playing the game, so I don't really need to edit this character, I'll just create another.) There is also the excellent Baldur's Gate Aaron O'Neil savegame editor, but I try not to use it, since it seems to kill my motivation to play the game.

Back OT: :D

Early on in BG2, whilst still in the first dungeon, the players come across a scroll for an Air Elemental, for free. (I was sure there was another, too —— for a Nishruu? —— but I have had no luck finding it in my recent savegames. :/) Mord-swords are a level seven spell, whereas there is the level six spell to summon an Invisible Stalker, which is unaffected by mind flayers.

Remember that the Schools of Conjuration and Divination are mutually incompatible, so a specialist in either school cannot cast spells from the other. (Specialist Mages can cast an additional spell per level each day.)

Wizard Conjuring Spells, Level, Type, Duration - School:
4th Conjure Minor Elemental (1 turn + 1 round/level of Spellcaster) - Divination magic, prohibits specialist Conjurers;
4th Monster Summoning III (4 rounds + 1 round/level) - Conjuration;
5th Animate Dead (8 hours see Mastering Mêlée & Magic) - Necromancy, no specialist Illusionists;
5th Summon Elemental (1 turn / level) - Divination;
6th Invisible Stalker (9 hours) - Conjuration, so prohibited school is Divination;

also
6th Summon Nishruu (1 round / level) specialist Diviners prohibited.
…

Now 7th level is very powerful magic, with
7th Mordenkainen's Sword (1 round / level) - cannot be cast by Conjurer nor Enchanter specialists;
7th Limited Wish (cannot be cast by specialist mage Invokers)
7th Cacofiend (15 rounds) - Conjuration.

________
edit: adjusted duration of Animate Dead.
edit 2: added sword

there is a Hakeashar scroll in the slums as part of J curse quest but some people mod it out as too powerful... I'm pretty sure you have to not bribe the wizards and kill them instead but it's been a few years

Aha! That was the one I remember and haven't encountered yet (in this play-through) so thank you for that. :)