Building a Tower takes strategy, patience, and a LOT of resources. The Tower is probably the most expensive town in Heroes III, however, if you do it right, the results can be phenomenal.
The first thing you should do when you start as a Tower is to build a Lookout Tower. As much as you want to build a Village or Town Hall, the Lookout Tower, which is unique to the Tower, gives you an instant advantage over your enemies. You can immediately ride out and claim mines, sawmills, or other resource suppliers. Use this advantage well, you’ll need all the resources you can get.
The following days should be spent building until you have at least a Tavern, a Town Hall and a Citadel. Once you have these buildings, you have to make a choice, which is so integral to the game, it is part of the title: Might vs. Magic.
The Tower Mage Guild is hands-down the most powerful in the game. The Guild goes up to a level 5, and the unique building the Library gives you one extra level 5 spell. However, both Mage Guilds and the Library are expensive, and require huge amounts of all resources,
On the other side of the coin, the Tower might buildings can crank out deadly armies at will. However, due to that fact that most of the troops are magic-related, the Tower creature dwellings are very expensive in resources. The Mage Tower (Magi), Altar of Wishes (Genies), Golden Pavilion (Nagas), and the Cloud Temple (Titans) all require lots special resources, such as crystal and gems.
As you can see, barring a glut of resources falling in your lap, it is nearly impossible to get everything you want. You need to make a decision as to whether you want to start with a small contingency of troops, backed up by heavy magic, or a bigger army with less magic power. You can, of course, try a hybrid of the two, but, unless you do it perfectly, this is even harder than a clear-cut commitment.
So, now that you’ve explained it, which path should I choose? Well, it depends on what kind of player you are, and what kind of map you are playing. If it is a small map, chances are that a Might strategy will be most effective. If it is a larger map, a more balanced attack backed up by magic may work better. The final choice however, is ultimately yours. Experiment, and see what works best for you.