Magical Sheild is a defensive spell similar to Invisibility which will protect your followers from direct spells from enemy Shamans and fireballs from Firewarriors. The spell can only be used on followers but not your shaman. You receive Magical Shield from a Vault of Knowledge on level 14: Attack From All Sides. The Magical Shield spell is not in the Default Multiplayer Restrictions.
Firewarriors have a magical attack similar to blast, so when you see a lot of firewarriors coming to attack your base simply cast Magical Shield on your own followers and they will be resisitant to the enemy firewarriors.
