Extensive Guide: The Wizard==
Note: This is an extensive guide and will not apply to begginners.
Upgrading the Wizard
The wizard is a curious unit with a very unique upgrading pattern rivaled by only the pheonix and healer.
For his first two upgrades, he is primarily a support/ranged attacker. He can only strike one unit at once and is rather helpless against swarms of units, paticularly fast ones.
As you progress and obtain the light wizard however, strategies involving the wizard become vastly different. He will be able to take out loads of units with just a few effortless strikes. Also, his range allows him to easily kill reaps before they get to him.