This is one of the more difficult waves. Focus everything on magic attacks. The most difficult player I won with was a dwarf gun-powder unit. Went like this
- Wood Elf Warrior
- Fire Mage
- Elven Healer
- Elf Lion Guard
Then auto-summon some mix of Pathfinder, Fire Mage, Wood Elf Warrior, and Elven Sniper.
Research: Magic Imbuement (if you do not start with a magic weapon), Mages Imbune