1. Hah! Good to know about demon summoning. The description that "the demon units are outside of your control" made me ignore that tech.

2. Tyrant is surprisingly buggy, in that if you customize him, you can no longer train a darkling scout or the urxen settlers from your cities.
It's probably why they have the lowest completion rate of the 8 different leaders, at 2.9%.

3. Those units are OP, but needing 6 sovereign skills before you can snowball can be tough.
I find many of the other sovereigns have combos that come out earlier.

For example:
1) Frozen Realm can turn terrain into snow after combat (it's lv2 sovereign skill). The thing is it often creates terrain that lets you settle there, so they can quickly get a ridiculously large empire.
Who needs to be scared of the sorcerer king when you have an insane number of settlements generating troops, logistics, and mana? :D

2) Tinkerers unlock enchantment slots and then powerful enchants, allowing them to quickly put together a high quality army.

3) Priestesses can actually recruit Wanderers who are ridiculously tanky right from the start.

I feel there is no sense in playing custom nations.

* I found the death nation + the hypnotize spell to gain control of other units is the most OP stuff. With the undead you can get bones and forge with that to equip everyone. + The undead hero can gain control of enemies even if you dont customize the spell.

* The abilty of settling everywhere is relative. There is no incentive to do so because the dude will be mad and send more powerful units sooner.

* The other thing is that the priestess (?), if i recall correctly, or the forest one can cast better enchantments. So units can have more initiative, armor. hitpoints depending on the essence.

so: hypnotize+undead+enchant of 5 or 6. The most OP.

the super stack will have one of the SC wargs to haste everyone, a wolf and a priest to buff attack. And units with multiple figures to multiply forged weapons.

*yeah, i played tinkerer first. Its a micro hell but the enchants are very cool. Also the summon weapons can be wielded by everyone.

The custom tyrant bug for producing settlers and what not is fixable. There's a thread on here somewhere the explains the detail. Sucks they never added it to the game directly, but there IS a fix with a small edit to the files. I just don't remember what it was or I'd post it here myself for ya. I do remember it was super simple. Minor change to a line or 2.