- A growing army consumes gold which requires expansion, which requires an even larger army, etc. Turtling is slow death at least until the very late game when you can get by with heroes and a couple stacks of high level units.
- If you need to free up resources, send troops on suicide missions instead of disbanding them. Disbanded units like to wander around "freeing" your towns and gold mines. They will occasionally attack you at the worst possible moment.
- You can use some units' abilities out of combat, by double clicking on their portrait. Clerics in particular can heal other units in the same stack.
- Cheap spells are the best spells. Always get at least one orb of Air and one of Life. This gives you access to Chain Lightning, one of the best offensive spells in the game (damages 4 units with a chance to stun for 1 round) and Summon Eagle, a very fast flying summon that can explore, loot one hex towns and can defeat one or even two level 1 units in a pinch. Also Water 1 for Healing, though Life offers a weaker work-around.
- Conserve movement as much as possible. When attacking with a stack of units, select the one with the most remaining movement by left clicking, and then right-clicking under it's portrait. When it attacks an adjacent army, the rest of your army will be pulled into the battle without wasting any remaining movement points.
- Regarding hero creation, it's best to focus on either pure combat or spellcasting. With spellcasting, prioritize researching Cosmos domain (purple) spells until you get Town Portal. A hero with Spellcasting 4 or better can cast Town Portal every turn, effectively defending all of your cities simultaneously. Combat heroes benefit from round attack, first strike and wall climbing. Any remaining XP points are best used on increasing their stats and speed. Every hero should have some form of long range attack as well.
- Take Life Stealing + Cold Strike at the beginning (you can't do this on further level-ups), trivialize the game. Then get First Strike, Parry and stats. Cold Strike freeze is the best incapacitation, this combined with Life Stealing will allow you to survive most attacks early and everything later on. Heroes are horribly broken in this game, I used one to beat 32 top-tier undead units in one fight.
- You can draw a town's defenders into the open by attacking an enemy stack that is outside, but adjacent to the town. If it is a four hex town with only one stack of defenders, approach them from the diagonally opposite side and you will fight each other inside the city walls!
- Don't be afraid to loot or even raze towns if you already have a decent income. Keep the initiative, and keep your armies fighting instead of waiting around. You can also rebuild towns/mines/farms/other structures if you have access to a Builders' Guild.
- High level summoning spells are a waste of mana. For the price of one summoned dragon you can permanently haste three flying units as a deep strike force that covers twice the territory, or you can buff an entire army in preparation for a battle. (Bad example here, dragons (and other fliers with ranged attack, like the Air Galley) are very strong - land armies without archers are completely defenseless against even a single frost drake.)