I am easily bothered by small things, and one of the small things that has bothered me is Trolls. You get four Troll summoning spells in Dominions 3: two for the land trolls, and two for the sea trolls. You can either summon a powerful troll king & his court, or you can summon one single troll. However, when you summon the king & his court, you also get a number of "other" trolls. War Trolls, Troll Moose Knights, and (Sea) Troll Guards add an interesting mix to the trollish armies.
But the only way to summon the "other" trolls is to summon an entire court of trolls. That's expensive! It's also excessive in many circumstances. What if you just want to add a few more Moose Knights? What if one of the Troll Guards dies in combat, and you want to replace him? You're stuck.
This mod -- More Trollz -- removes this annoyance. It provides three new Conjuration rituals to summon the "elite" trolls. The trolls themselves are not altered from the base game. Only now, you can actually summon them without having to summon a whole court. Simple, no?
The "elite" trolls are more powerful than the "standard" trolls, so I had to do something for game balance. I did two things, actually. First, the new spells will cost three gems per "elite" troll. Second (and more important), the new spells are also one level further up the research tree at Conjuration 7. Hopefully, these two tweaks are enough to preserve whatever usefulness the original "Contact Troll" spells had.
(Although I suspect they don't have much usefulness anyway. One mage-turn per troll is the real cost of the spells, and that's a bit steep....)
I don't claim that More Trollz is a groundbreaking mod, but I find it to be useful. If you like it, you're welcome to it. Perhaps you can use it as a template for your own spell modding?