What's the most overpowered strategy you can think of?
It should not use bugs, let alone cheats, and be applicable at as high difficulty levels as possible. It should not rely too much on a good start, but it's A-OK if it can take advantage of some factors that may randomly occur.
RACE: Men blood, scouts, heroic, wanderlust, vulnerable to magic
LEADER: Beastlord, air, water, brilliant, attuned, wealthy, clumsy, sword
Settle a city with at least one essence and cast "Inspiration", and "Meditation" if possible . If no essence is available, settle in the tile with maximum materials, disregarding forests and rivers. Target "Civics", start building pioneers, lower taxes, hire the hero, start exploring with both heroes, ignore monsters unless they interfere with your exploration.
Start any safe quest, and take it to the point you have to fight. This is so that no AI steal it.
Once you have explored a bit, and got the nearby safe loot, make a plan. Are there beasts worth taming? Do you need to raise your penetration (you get 3 per level) to tame them? Are there areas for settling? Can you make those safe with the two heroes and easy to tame beasts? (Remember, you are getting mana from an attuned sovereign, and maybe mediation)
Once you have researched 'Civics' start rushing pioneers, and settle the spots you have discovered. Rush some club wielders with "Muscle", "Ironskin" and "Health" if you need them for your planned settling locations. If you need the punch, research "Training" for shields, and make sure you mark their armor upgradable. With or without the clubbers, tame the beasts worth taming, and clear the lairs that may interfere with settling. Do not kill any monsters that you do not need to kill, unless an AI is threatening to poach them. Settle 3 or 4 cities. Do not overextend.
The champion should become a governor, the sovereign should become a defender, and focus on "Trainer" and "Tactician".
Your research path is "Civics"->"Restoration"->"Knowledge"->"Administration". With that, you can have your cities at 2% unrest with low taxes once you link your dominion. Do so. Build cash buildings, research buildings, unrest buildings, in that order. Make the city with the highest essence a fortress. Make enough towns so that your fortress can get to level 3 (i.e. do the math to see how many grocers you need.) The rest can be conclaves.
Once you have started your economy, target "Henchmen" and solve the easiest available quest. If you can't, with the beasts you have tamed, two heroes, and possibly some clubbers, you must have the worst luck ever, so go do something else.
Design a henchman with "Bard", "Shieldwall", "Potential" and call him "Newbie". Rush as many newbies as you can, and keep your fortress building more. Influence is likely to be an issue at this point, but not for long. Stack the henchman with the sovereign, unstack the champion if he is stacked. Use the champion to make cities grow or something. You won't need him anymore.
If there are horses nearby, research "Mounted warfare". When you need more food to grow your cities, research the appropriate tech.
Your new research path is "Heroes" (quest maps) ->"Enchantment" (lightning hammers)->"Tireless March" then balance between higher construction and better fortress buildings. I.e. your new henchmen should be coming out of your fortress as tough as possible.
When your research reaches that stage, update the newbie design with horses (if available), leather armor, lightning hammers, and trinkets to increase fire resistance and damage. Cast auras on your fortress to get the best henchmen you can. Have them become defenders, with a minor in mage if possible, get "Stun" and "Shieldwall", and focus on "Potential", "Trainer", and "Tactician". Make friends with Pariden, keep them alive and buy spellbooks for your henchmen. Cast "Tutelage" and "Tireless march" on as many as you can afford. Kick beasts and troops from the main stack as space grows limited, and when the rejects become strong enough, have them form a new stack and do the quest loop. What's the quest loop?
1. Spend Gildar to buy quests maps
2. Use quest maps to generate quests
3. Solve quests to get influence (and Gildar from loot)
4. Trade influence for Gildar.
5. Back to 1.
How good is this strategy? On ridiculous/ridiculous, I had my sovereign and 6 henchmen at level 33/34 around turn 100. They killed three ashwake dragons without letting them act once. The best part, the game goes very fast, because you do not care about cities, expanding, etc... and you just use you main stack.
I'm about to try it on insane.
Note: If you feel lucky, you can take "Betrayers" instead of "Wanderlust" and "Scouts", and get your quests maps from Altar. This relies on luck, because Altar may be far away, which will leave your megastack too far from your homeland to defend them. But you will be able to flip AI cities at a rate of one per five turns easily.