Slitherine

Hi!
I really like Caster of Magic. However, with both gold and mana being more easily accessable, the rewards coming from the average mob lairs don't feel too rewarding.
In vanilla MoM, 100 gold and 80 mana could mean a lot, but in Caster of Magic - being more difficult overall - this doesn't feel much.

So my recommendation is to balance this out.

In the first few turns, those rewards are worth several turns of production or a common unit or two, so I'm not sure that they're inadequate rewards. You're probably taking them with your starting swordsmen, which only costs a few gold in lost taxes, so they're really a great investment. Large rewards would make initial placement of such lairs too game-determining: have a good lair or two next to your capitol = win; no lair = lose.

Would a unit enchantment be a good option for treasures? Attack a lair and one of your units gets Bless, or Flame Blade or whatever? That might be interesting.

Unit Enchantments could indeed be a nice reward.