I watched a video a few days ago that claimed Shadow was the weakest affinity; I watched another yesterday that made a convincing case that it's actually the strongest.

So anything I write here could be and probably will be refuted sooner or later.

Meanwhile, I make these brief observations in the hope that they may be of some assistance to help beginners ease into the game so they can better explore its many and varied mechanics for themselves.

IMPORTANT NOTE: a recent rebalance patch has specifically nerfed many of the suggestions made in this guide, which I guess confirms that they were in fact pretty decent suggestions! I'll update the guide after I've familiarised myself more fully with the new regime.

Many claims have been made that the AI cheats. The easiest way to challenge this assertion is to play with one or more allies, so we can watch how they play. Before doing that, though, we might as well pick a realm that plays into the strengths we are going to give our civilization.

Start a new game, and select Custom Realm.

Realms> create realm> customise realm> and you can choose some traits. Click on the icons to get the choices. Crystalline Abundance and Wondrous Past will suit us, together with others to taste - or none of them, if you prefer.

Realm customisation allows you to set number of players, starting distance, etc. Let's choose 6 players for now. Starting distance on 'standard' is pretty close; if you prefer not to start in your neighbours' back yard, consider using 'far'.

Now we go to Advanced Settings> Factions> allow Teams. I suggest AI difficulty normal or hard. Select Team 1 for yourself and whoever you want as allies, with the others not teamed. We want hard or very hard AI for your allies, and not harder than hard AI for your foes.

Next, we need to create a faction. Keen-sighted and Arcane Focus will be useful traits.

For Culture we want Mystic, Mana Addicts (if you have unlocked it, otherwise Runesmiths) Wonder Architects, and Tome of the Horde, then say Champion (Wizard King is also fine). Go to your realm, check your free Wonder and your allies, then start building a Shrine.

Setup is now complete.

Depending on how many allies you have chosen, you may need to do little more personally than survive until one of them wins - but we should aim to do better than that.

Our build will depend on stacking buffs onto our basic unit, the Tier 1 Arcanist, until they are capable of one-shotting pretty much every other unit on the game. Our main focus will be Astral, with some Chaos, Nature and Order thrown in. We want these Tomes and skills:
Horde (for Spawnkin)
Faith (for Army Heal, Faithful Whispers)
Roots (for Vine Prison)
Mayhem (for Mark of Misfortune)
Amplification (for Frenzying Focus)
Beacon (for Mighty Meek)
Pandemonium (for Havoc Magic)
Cycles (for Projectiles of Decay)
Astral Convergence (for Astral Shattering).

Of course you will need to select other picks as well, but concentrate on these. If nothing appeals on a selection, just select the cheapest one.

If you want to go for a Magic victory, you can then finish with Teleportation and Astral Mirror to gain access to Tome of the Archmage.

Empire Development
(1) Astral: The skills below the branch are mostly useful. The ones above are more situational - for emergencies.
(2) Order: Situational, mainly helpful if you want multiple vassals.
(3) Nature: Take the first 3 abilities.
(4) General: Situational, though roads and the embark ability are generally useful. Forced march is great if you also have tireless march (Chaos)
(5) Chaos: Call of Chaos is good for getting early cheap units to defend your Arcanists. Impressment helps save gold.Tireless march is great with forced march (General)

Army Build
The basic build is 3 arcanists per army, together with a soother for healing, and a couple of units for protecting your arcanists. Spellshields are not bad because they have stun, but any decent blocker will do. Heroes to lead each army if you have them available.

Hero Build
Battle seeker, experienced leader, and precision training are all useful, and any signature skills that give a summons - for more bodies to be blockers.

Personally, I run my ruler as a mage, followed by a tank, and then it depends on what heroes and equipment I have available for the others.

(a) The AI forward builds quite aggressively. Initially, you want to focus on (1) securing your same-race vassal and then (2) setting up a couple of outposts you can later turn into cities. These can be just one or two tiles from your capital, if space is short. Cities in AOW4 don't need to be massive (12 to 15 provinces is fine) and if you want to go for a magic victory you will need 3.
(b) A maximum of 3 armies on either side is allowed in battle, the attacking stack and the two highest-value stacks within range. On Auto-resolve, victory will generally go to whoever has the highest-value total army. Remember though that in manual mode, Arcanists with all those buffs will fight way above their nominal worth.
(c) Vine Prison has been called the most overpowered spell in the game. It's invaluable for breaking up enemy melee attacks.
(d) Keep your cities happy. Promote them to level 2 when they grow to 5, and build the Tavern - and the Bathhouse later.
(e) Because game maps are procedurally generated, you can have a 'good' or a 'bad' start no matter how good a player you are. If you want to check what the map holds early on: Save the game, then CTRL-ALT-C will bring up the cheat menu. Type Barentz, the whole map will be revealed. After reviewing the map, quit and reload your save, and achievements will still be available.
(f) Magic victory is by far the easiest, because the AI tends to hang around their capitals with huge stacks. On the other hand, the 'raiding units' sent to molest your Magic victory buildings will only be worth around 2000 overall - easy meat for your endgame army.
(g) Astral Shattering is basically a hard counter to any enemy's attempt to get a magic victory, because their magic victory buildings are always visible, and even if they have a spell jammer, you just need to stand a summon unit (of which you will have a few) on it for one turn to neutralise it.
(h) Unlike Civ or similar games, AoW4 is not balanced around several hundred gameplay turns. Figure probably less than 100 turns, and certainly less than 150 turns, for the average game.
(i) Importantly, spells in AoW4 can be cast, but not launched immediately, granting the player a strategic reserve of potential actions. It's not unusual late game to have a number of summon spells researched, and these can be cast and held in reserve for when an emergency stack is needed. Similarly, spells that affect enemy stacks can be stored up and cast at once for an instant nuking effect.
(j) Overall, AoW4 is a complicated game with a mass of detail, far too much for this brief summary. The button marked "i" at top right screen is worth consulting in case of need.

Onward to victory!