Playing as Daemon Sultan
During the first turn, typically Daemon Sultan Summons free Cultists for a while. Near the end of the turn, build a Gate and either Move a second Cultist to it, or Summon a Larva. That’ll use up your 4 Power. Yes, someone may Capture one of your Cultists, but it’s cheaper to replace it (free) than to flee, unless you fear letting that player gain the Power next turn.
Your hardest Spellbook to achieve is the Abandoned Gate; often, you can’t accomplish it until you have a Chaos Gate available. However, in theory, you could get the “every other player chooses whether he receives 1 Power or 1 Doom” Spellbook, in your first Action Phase but it can be risky giving your foes that early boost.
In general, you needn’t suppress enemy players in the early- to mid-game (unless one pulls ahead drastically). Instead, you have several tools to use in boosting players who fall behind—let them pull down the leaders. You are, by and large, a Faction which thrives by keeping your enemies on an even playing field.
One of your big decisions is how much to pay for Avatar Thesis—you could, of course, pay nothing, but then you must pay it back later, when Avatar Antithesis costs 8! In general, a cheap Thesis makes sense, because Power is precious in the early game. But, it can be useful to get your second Great Old One out early, too. Some players like paying 4 apiece, which at least has the virtue that you know what your Avatars all cost. Don’t forget, however, that if you have a 0-cost Avatar, you can Sacrifice it cheaply to keep another, better Avatar alive via Synthesis’ Cosmic Ruler ability. Don’t forget to re-Awaken your cheap Avatar.
Your Spellbooks activate once per turn, so you need to position yourself properly to maximize their value. You’ll seem weak early, but later your three Great Old Ones help you surge ahead. Experienced enemies will figure this out; don’t fall into the trap of spending your entire turn managing Spellbooks and slacking off on essential tasks, such as building Gates. Eventually, you may have only your Chaos Gates, but if you can manage to perform Rituals, you can get up to 3 Elder Signs each time.
A core Spellbook, but pointless to take as your first one.
An excellent Spellbook, though it may not appear so at first glance. You get an Elder Sign, another player gets saddled with a hard-to-protect Gate in the middle of nowhere, and you get a new Cultist to place for free with Psychosis.
This gives you a comparatively safe Gate, and also sets you up for the Terror weapon of Animate Matter.
Your signature move. As the click-bait ad goes, “Other Great Old Ones hate him!”
It requires you to put Thesis in harm’s way, but if he’s cheap, you shouldn’t care.
Lets you set up for lots of stuff and, unlike Undirected Energy, since you get Units immediately, Antithesis is protected.
Thwarting Daemon Sultan
Daemon Sultan’s great strength is that he can destroy your infrastructure and help your rivals. His great weakness is that it takes him at least three turns and 19 Power to set up all his Great Old Ones, which means he has a long, slow buildup.
You can pre-emptively hamper him by checking which Larvae he has out. If he doesn’t have a relevant Larva, he can’t Awaken that Great Old One. You should also kick him off his Chaos Gates. An Abandoned Gate is still good for you, after all, and you’ll need the Power to rebuild your lost Gates.