I am on my first playthrough playing conjurer and I'm trying to find out the difference between stun and slow.
Stun description states:
>Cast your foe into a brief powerless daze, slowing warriors and rendering spellcasters unable even to move.

Slow description states:
>Deprive a creature of its speed for a few moments.

Against the ogres I tried them on slow seemed like the better spell since it lasted longer. Both consume the same amount of mana. The stun description makes it sound like it's more effective against wizards. I am not exactly sure how I am supposed to know what a wizard enemy is. Does the effect maybe scale with their mana pool? Or does it depend if they can cast spells?

Also I took a relativly long break from the game. How exactly do you summon creatures again? I remember how to charm them, but not exactly sure how to summon them exactly.

Maybe someone can clarify this for me :)

Stun is idd better against wizards because it will stop the from casting spells(but atm cant tell you which enemies are counted as wizard but you may want to look for any range creature) while slow is more effective against melee enemies.

About summoning monsters, open your beast log or w/e is called and in there you should have a button to drag and drop to your hotbar IIRC