Gems of War: Max effective leveling up kingdoms (up to level 20 - game version 6.7, 1 Jan 23)

An order to level up your kingdoms using gold and deeds for maximum efficiency.

Introduction

At this very moment, there are currently 37 accessible kingdoms in the game that can be unlocked and upgraded. There are also 4 "kingdoms" (or rather "planes") which you can't see on the map, and 37 underworld factions, which are actually included in all 37 upper world kingdoms.

Now, every accessible kingdom has two possible ways to upgrade. In the ideal world, the player is supposed to go both ways. Every upgrade means more power and overall game bonuses to the player, including daily income of all in-game currencies (gold, souls, glory, gems).
The first way is more simple and presumes that the player will spend some gold to level the kingdom up to level 10, and then some more gold plus special coloured deeds and writs to level up to 20.
The second way is more closely connected to the overall player's progress, as well as the progress of the game content development.
To keep this guide short, I'll tell you only the strategy to the first way of city upgrading.

You can also check the official guide for kingdoms leveling here: https://gemsofwar.zendesk.com/hc/en-us/articles/360000491816-Levelling-up-Kingdoms

Step one: leveling up to 10

Step one is simple: you need a guild without gold investment rule, you upgrade all your cities up to level 5, then 10. That can be done in the first ~100 hours of your game time. Focus on one town, level it up to 5, then move on to the next one. Then all that again, all the way to level 10.
The main principle of the upgrades to level 10: the first ones are the towns with the Magic skill bonus. Then Attack skill, then Life, and then Armor. Always in that order, if you want to maximize the effect of all your gameplay processes.

List of Magic skill cities: Blighted Lands, Darkstone, Karakoth, Silverglade, Zhul'kari

List of Attack skill cities: Blackhawk, Dhrak-Zum, Forest of Thorns, Pridelands, Sin of Maraj, Suncrest, Wild Plains

List of Life skill cities: Bright Forest, Broken Spire, Divinions Fields, Ghulvania, Khaziel, Maugrim Forest, Merlantis, Pan's Vale, Shentang, Stormheim, Urskaya, Vulpacea, Zaejin

List of Armor skill cities: Adana, Dragons Claw, Drifting Sands, Glacial Peaks, Grosh-Nak, Hellcrag, Khetar, Leonis, Mist of Scales, Nexus, Sword's Edge, Whitehelm

Step two: leveling from 11 to 20.

Now, the most interesting part, the leveling with the deeds and writs, up to level 20 (again, it's wiser to get all kingdoms to 15, and only then go for 20). In that way, After you're done with leveling all the cities up to level 10, you need the guild which actually finishes at least some of the weekly tasks and events. You will gain more writs and deeds that way, but now it is supposed that you drop some of your gold as the guild tasks progress. Also, keep a close eye on your daily events, the most of the writs you'll get from there.

The basic principle of leveling from 10 to 20 level is the same, Magic, then Attack, then Life, and finally Armor skill. But! Now you need not just gold, but also some specific coloured writs to level up towns. And this gets much more complicated after the level 15, when you need not just simple writs, but much rare Imperial ones, and not simple deeds, but the whole tomes of it, and every tome worth 50 coloured deeds.

Besides that, you need to keep in mind the underground locations, because you'll need bonuses for your Delve runs much harder than any +1 for your skills. Also, some of the underground factions are much easier than others, so, if you're interested in maxing all the factions, maybe you need to form an additional priority list. Or just follow that order that you first you level Magic undergrounds, then Attack, and so on...


For your Fire (Red) deeds, you upgrade Pridelands, Sin of Maraj, Wild Plains.
Then Dragon's Claw and Grosh-Nak. And then Mist of Scales and Hellcrag.

For your Air (Yellow) deeds, Suncrest first. Then Pan's Vale and Divinion Fields.
Then Whitehelm. Then Shentang. Then Adana.

For your Nature (Green) deeds - Zhul'kari! (the only non-purple magic kingdom).
Then Forest of Thorns. Then Bright Forest, Maugrim Forest, Vulpacea and Zaejin.

For your Ice (Blue) deeds - Merlantis and Stormheim.
Then Leonis Empire, Sword's Edge, Glacial Peaks.

For your Magic (Purple) deeds - Darkstone and Silverglade, Blighted Lands and Karakoth.
Then Ghoulvania. Then Khetar.

For your Stone (Brown) deeds - Blackhawk and Dhrak-Zum.
Then Broken Spire, Khaziel and Urskaya. Then, finally, Drifting Sands and Nexus.