Tactics for playing against Sylvan.

The AI in Heroes of Might and Magic IV is quite simple. It never uses the portal to summon creatures. However, when playing against a human opponent, the portal becomes a crucial element. Specifically, I'm talking about Mantises and water elementals. I find elementals to be more dangerous. Buying a dozen and distributing them across stacks allows you to hide behind them from ranged attacks, as they are difficult to kill. Meanwhile, a nature mage with his summon or an archer can wreak havoc.

P.S. I have the "Armageddon's Blade" expansion. Does anyone have a link where I can find instructions on how to install a program for playing online?