Quoting Blaze of Glory,
reply 6
Imbue a low level champion, usually spouse first. Every level up is +3 essense, so quickly I can have a sovereign with 20+ essense and 2 oe 3 others with 6-12. Then the kids grow up and start with essense and level up. By mid game I have at least 6 channelers or more. that are pretty powerful
As to the spell that is -10 for everyone, can't miss. That needs nerfed badly. However, it should also be fixed that a squad or company only loses 10 for the entire group while individuals lose -10 each. (Lessen the overall damage, but have it apply * the number of soldiers in the group.
I can see it, but only has a super high mana spell and a chance of each unit resisting. Having the monster in the campaign cast it with 3 mana is absurd
I imbue using my caster Sov every Champ that has reasonably high Intelligence, before my spawn mature in the early mid game I'll have usually 8+ casters I try to keep 2-3 caster types in each army stack for teleporting and reserve mana based attacks as a last resort due to the long mana recoup delay but I feel it adds to the RPG feel - think pen and paper D&D... Melee types could go and go, but Casters had to use there brains over their brawn and use the right spell at the right time so as to not just waste magic... It was special out of the ordinary... ahh yeah Magical, duh 
Accordingly, my caster champs have 11 of so Con/HP to just survive the -10hp AOEnevermissspellofdoom (boy what I'd give to have that in my repertoire, no it's seriously OP) while the rest go into Essence/Wis and Intelligence. Additionally, I rely heavily on summoned elemental armies augmented by man-flesh/man-troops. I actually thought most people were using mostly summoned armies until I started reading the forums... I thought given the games title that the devs rather expected we'd go the summoning route...but you know what makes this game cool is that there are so many paths to success of victory... the shame is the bar is set too low.
Anyhow back to the point I am trying to make with this post is that by having so many channelers/casters that I can put them on a kind of rotation to allow others in teh stack to rest several turns while others are active. They nearly always have mana and if I do need something extra its there but not w/o a cast the rest needed afterwards. IT's just that the magic should be stronger than melee/archers but its not. It's on par but the down time can blow chucks unless you create a solution to work through the limitations. Also if I need to make more real estate to grow my towns (works for shorelines) then I TP my caster stack and give the sea and shoreline a facelift and voila growing room. But yeah thats a drainer. I like having to make tough choices. That's what makes the game enjoyable. All easy choices would make the game ... well easy. Granted there is the AI and rework and bug fixing that needs to be done. I still like the game a heck of a lot.