Why can't I train Mages?!

Most likely they require crystal to build.

Edit: Oh they don't show up at all? Hrmm.. likely still something not researched for them then, Its possible they need another Item you haven't researched.

Maybe you clicked "Hide" in the Unit Design menu in some other game ?

No, I didn't.

It would be helpful if troups and buildings had a list of their prerequisites in their tech tree description (the small hint text that pops up when you mouse over the respective mini icon under the tech tree item, you know).

Or if their would be a piece of documentation that list them. Would help a lot with tacical research item selection.

Do you have a functional Crystal mine? I could not train mages too in my previous game, until I has hooked up a Crystal mine and has gained Crystal income. After that, the Mage was available.

I would recommend going in and designing new mages, as far as I remember, the mages needs the "Blasting staff" (whatever its called, ranged attack staff) and a similar elemental ring (+1 damage, +25% resist to one element).

If you have both of those, it beats me, but as I said, go design some new mages

Sincerely
~ Kongdej

Update:

I finally found out how it works.

Units that require a certain ressource to train only appear in your training selection list if you have AT LEAST ONE of those ressoures in your ressource pool.

In my case the Mages did not appear in my training selection list until I had a single crystal.

Once I had a few crystals they were listed along with the Chosen. And if you click on them you see that they cannot be trained because training requirement is 20 crystals for Mages and 36 crystals for Chosen.

Same goes with certain buildings btw.

"mages" are just dudes with magic wands. they don't actually have any spells. all they have is one of the elemental staffs, which fires a bolt of elemental damage. These staves are unlocked at Enchanting i think, and later in the tech tree there's better ones at Arcane Weapons.

Anything magic requires crystals to manufacture. these staves are no exception

Thank you for telling us this, hadn't really noticed this (I do try to design all my own units myself).

Sincerely
~ Kongdej

Yes, they're just wand-wielding peasants, as others are sword- or bow-wielding peasants... Am I the only one to find strange you can not get any real mages, except heroes, and nothing resembling elite troops (even the most armored troops have crappy hp and get killed fast ??

Well, elite troops are leveled troops.  If you have a high level fort, your troops might come out level 5, with bloodthirsty and act first during combat, + 30 accuracy, extra armor from buildings and have bonus hp, defense, fire damage...just from being built in a leveled fort with enchantments on it.  Then add that to any traits, items, weapon and armor you add to that.  Their weakness will come from large monster with overpower or spells and abilities that due multiple damage per soldier in a unit.

Agreed Lord Xia, but about mages ??

We should have buildings enabling spell-like skills to add as traits to "real" mage units, so they could cast Burning Hands, then Flame Bolt with an upgraded mage building, etc...

The game has tons of abilities that are monster-only, it would be fun to have some available to player units.

The Champions and Sovs are the spell casting mages, it's what makes them truly special.  If you want to train some spell castors, than play as Altar and make magic using henchmen.

I think Mages should have at least one spell, unique to the faction. Then, players designing Mages can create Mage that can cast one spell available to the Sovereign (maybe limit this to lv 1-2 spells). This will make playing experience varied greatly.

We use to be able to give units the ability to cast certain spells, maybe we still can and I haven't been paying attention.  I admit, the magic tech tree is the side of things I know the least about.