Age of Wonders III

Necromancer spell, conquer a city choose to burn it down then cast the spell at the city's ruins.
Alternatively, once you have the spell researched and available and enough mana crystals to cast, raze one of your own cities (even your main city) then cast it on it to unlock.

I couldnt find the button to create my own leader so I had to do some research, so to save you the work. The button is in a dropdown menu on the top right of the main menu screen under your profile name.

This is tricky if you are not used to downloading mods from the workshop, basically, go to the workshop, find a scenario and subscribe to it.

Then, when you first run the game, at the Launcher small window (not in the game), go to the User Content tab and click on the Update button, the scenario you subscribed to will appear. Click on Play at the bottom of the Launcher.

As you get into the game's Main Menu, click on New Scenario then go to Community tab, pick the Scenario you downloaded and as the game is launched and starts the achievement will unlock.

Cheers!

To increase your chance to get this unique human hero, start as a Human Leader and in the Map setup area, go to Advanced Rules, choose Random Heroes match player race. You can also boost Max Number of Heroes to 20 if you want.

As you start the game and the first hero asks to join, you can pick the option " I require another type of hero" until the human Dreadnaught comes up and it will be Notch!

There you go 😃

I got this achievement without the city asking me to liberate them, but I sieged the city and casted a lot of unhappiness spells on it until it was rebellious (-1000 happiness or more) I then fought a unit adjacent to the city (so I really didnt fight for the city, just the adjacent troops and the ones in the city but without occupying it) as I won the battle, the city became vacant and they just switched to my side. The spells I used were Rally the Populace and Sunburst.

TL;DR I didnt get a quest for this achievement but still got it by making the city Rebellious and then wiping out the defending armies (without directly capturing the city by moving on the city tile)

I can confirm a naga city (dwelling) is in the 2nd scenario in the Golden Campaign and you can get this achievement by capturing it and absorbing it in your empire.

The city will be hostile to you, its in the middle area of the map, across the river where you settle your first 3 cities for the storyline.

The achievement will pop after 5 turns after you decide and successfully absorb it.

To get this achievement you need to charm an elephant unit.

In the Golden campaign, you will see these units roam around the map, they will never be hostile to you or capture cities or fortresses, they are harmless.

In the first scenario, after a while, you will get a heroine that likes to party and get drunk and if you level her up, she will get the skill to Charm.

Make sure you keep these elephants units alive until then, then using that heroine attack the elephants and charm them.

Good luck!

I was wondering why the AI never surrendered to me during the campaign, as it turns out, its disabled.

https://steamcommunity.com/app/226840/discussions/0/613940109885323364/

You have to play custom games against the AI and beat them in a major battle so bad, they decide to surrender.

This is a thread where the developer explains the mechanics. Diplomacy or difficulty has nothing to do with it.

https://steamcommunity.com/app/226840/discussions/0/152390014785646855/

I quote: "The surrender check is done after the AI looses a major battle. It then checks on how much army is left and how much economy is left and if this would allow it to recover. If there isn't, it surrenders. Do note all of those checks are relative, so the AIs stuff vs. yours."

Hope this info helps!

You can get this in campaign mode. Undead scenario, chapter 2. The city is to the south, on water, cant miss it. No need to worry about rng.