Heretic 2

Heretic II sets you upon an epic quest across an entire continent to find a means to cleanse a world infected with a deadly magical plague that has victimized the people of the realm. Exploring city, swamp, canyon, and dungeon levels, you use a variety of offensive and defensive spells such as the Sphere of Annihilation, Repulsion, and Fireball in conjunction with a magical bow and staff to defeat a multitude of insane plague-ridden denizens of Parthoris. Welcome to your new religion.