Auto-translated
Here's how I level up: Week 1 – skeletons and their upgrades. On day 2, I capture a stone and wood mine. I send 2 heroes to search for free mercury and sulfur. I build up to specters and a guild in week 1. With my main hero, I attack one type of neutral creature to get more skeletons. Week 2 – vampires and liches, citadel, capitol. After that, it's easy to develop with vampires. Week 3 – death knights and dragons, depending on how much mercury I find! By week 3, I have a pretty good army.