Gnolls are kind of my favorite race to play for non-Conjuring strategies, because I like getting aggressive early.

Here are my tips for how to maximize Gnolls.

1) Resist Magic is a must have. This means you need to either play all Sorcery or at least take 2 Sorcery books.
2) Alchemy + Warlord is easily the strongest Retort combo. Next would probably be Alchemy + Sorcery Mastery + Conjuring.
3) Of course you want to scout with a Magic Spirit to find good targets for early aggression.

4) How to Alchemy: Generally you don't need much magic right away, it's all about building units ASAP. So what you want to do is put all Magic power to Mana , and then convert your Mana to Gold to help rush the production of your buildings. This can also help by letting you reducing your taxes to prevent needing to build a Shrine before Wolf Riders.

5) The build:

The big advantage is of course Wolf Riders, which you want to be able to pump out as fast as possible. Generally the fastest way is:
Granary > Marketplace > Farmer's Market > Sawmill (Decision, is your production pretty strong? if so then > Stables, if its kind of weak then > Forester's Guild > Stables)

Once you have Stables you will likely want to pump out 2 Wolf Riders. The huge advantage of Warlord is that they will be Regulars without having to have build the Fighter's Guild. Typically after 2 or 3 Wolf Riders, I'll then build a Shrine and Miner's Guild, then make more Wolf Riders, then eventually build a Temple.

You should be able to use your Wolf Riders to take small encounters and weak nodes, typically Chaos, but the biggest prize early on is Neutral towns. With Phantom Warriors you should be able to take virtually any Neutral Town with 1 to 3 Wolf Riders.

Now just keep the flood of Wolf Riders coming and eventually ramp your taxes back up to higher levels and start doing research or increasing your casting skill.

Eventually you'll want to build a Fighter's Guild, but that doesn't typically come til mid-game.

As far as spell schools go, I think all Sorcery is best, but 2 Sorcery books with Nature is also very good for the cheap early buffs. If you can get a mix of Resist Magic, Guardian Wind, Resist Elements, Stone Skin, and Giant Strength, with Water Walking and Web, that's a super strong opening. Of Course with just 2 Sorcery books Guardian Wind is not guaranteed. Earth Lore is also really helpful in identifying targets. But still, I think all Sorcery is better for the Phantom Warriors and guaranteed Flying.

If you do not have Resist Magic, unless you get really lucky, you will be destroyed by Sorcery and Death casters: Confusion, Black Sleep, Weakness, etc., will just devastate Gnolls without the protection of Resist Magic.

Anyway, that's how I do it. It's all about getting aggressive as fast as possible. Rush the buildings until you can make Wolf Riders, then pump them out and take over. Don't be afraid to go straight for enemy Wizard capitals right away too.

I just quickly finished out a game with this setup. I took 4 Sorcery books and 4 Nature books on 1.51 Extreme - Huge land size.

Your spells get a little weak later on, but man this setup comes on strong, so it doesn't matter much.

For my starting spells I took:

Guardian Wind, Resist Magic, Word of Recall

Web, Resist Elements, Stone Skin

This gives you huge flexibility early on with tons of defensive ability.

I was able to take on Halfling Slingers, Shamen, Sprites, and various other stuff often with a single unit of Wolf Riders.

I started out with 2 units and took some encounters and a node, then got Brax and another unit and was able to quickly take out an enemy capital that was guarded by 6 Sprites by killing 2 units at a time with Web and then Exhausting and going back in. As the Wolf Riders hit Ultra Elite I was able to split them up and use a single buffed unit at a time to take on multiple wizards. Took out Kali in a Halfling fortress thanks to Guardian Wind, Resist Magic and Resist Elements. I got Giant Strength which helped also.

Basically, when everyone else is running around with Hell Hounds, Cavalry, Shaman and the like, your buffed your Wolf Riders are insanely powerful. Buffed Ultra Elites have 10 attack, 60% To Hit (Alchemy), 6 Shields (9 vs magic attacks), 6 Health, 13 Resistance (Resist Magic) and 6 health each (and 3 movement to boot!) This means a full unit is delivering 24 points of damage on average, ouch!

Since your units come out so early and start taking encounters to soon, and because they can travel fast to go from one to the next, they level up quickly. It's common with Gnolls to have Ultra Elite Wolf Riders when most other enemies haven't even build Fighter's Guilds yet.

Ever thought about endurance with the wolfriders? They get pretty quick to the enemies' range units.

The most important things Gnolls need are Flight and/or Web, so Life magic isn't a good option for them. The best way to play Gnolls is either all Blue or a a mix of Blue and Green. Noting worse than being shut down by Sprites...

Did they buff sprites or something? Seems like wolf riders should be able to tank the sprite shots and then kill them when they advance?

It may depend on which version you play. I play 1.5x, and in that version flying unit don't suicide themselves into non-flying units. If you can't attack a flying unit it will just sit there and you won't be able to win the battle. So you have to be able to actually initiate attacks against flying units.

Ah. That would make a difference, then.

So...you never use bowmen?

Gnoll bowmen? No. Only time has been close Sorcery nodes with Phantom Warrior early in the game. If you're trying to take out an enemy fortress half-way across the map in the early game Bowmen aren't going to work. Being able to get there in 4 or 5 turns is critical, not waiting 20 turns for 1 movement bowmen to get there.

So you could attack a node of chimeras or something with a single spearman and Doom Bolt them all to death while they sit there?

No. If the unit is more powerful it will attack, but it some logic tells the AI that the flying until will be killed if it attacks the other unit then it will not attack. So a single unit of Sprites can prevent you from being able to take a town with Torin for example, etc.

but a Great Drake will still chase you around the battlefield trying to kill you.

Exactly.