Tower tactics.

I never had any economic difficulties with the Tower faction; it's simply not necessary (as with any other faction) to build everything. In the early stages, improved Gremlins and Gargoyles are enough to gather resources, then focus on Mages and Nagas. And a few Djinns. If you develop a hero with good magic skills properly, that's enough. I rarely reach Titans; in the last game, I had five unupgraded ones, and compared to thirty Nagas, they were useless.
Regarding magic, I like to clone, teleport, and haste. I don't know how, but with this reduced army and a powerful intellectual specialist in magic, I easily defeated a Necromancer with a bunch of Vampires, Skeletons, Liches, Knights... a mage who was superior in level and parameters. P.S. Djinns are dangerous during sieges; they can cast "Air Shield").