The map can be downloaded here :
https://www.epicwar.com/maps/269490/
It is not a skill. When you click Mana Wyrm, you have access to damage and protection. Then put the mouse on "protection"
https://www.epicwar.com/maps/269490/
It is not a skill. When you click Mana Wyrm, you have access to damage and protection. Then put the mouse on "protection"
EDIT: Unless you're talking about the Mana Ray unit, which has the Mana Flare spell. If it's that one (not a custom spell), then night elf Faerie Dragon unit has it.