Thunder Storm

Place a devastating thunder storm in target 7x7 area.

Upon casting, electricity will flood the storm area. Then for 20 turns, electrified tiles will spread, and Thunder Tornadoes will randomly spawn.

Thunder Tornadoes are 2x2 in size and last 7-12 turns. Each turn, they deal 10-22 damage to all units within and have a 40% chance to stun.