Sulfur

Sulfur is one of the four magical resources (along with Crystal, Gems and Mercury). Its symbol is . Sulfur is required to construct several buildings and to hire Red Dragons, Black Dragons, Chaos Hydras and Rust Dragons. The primary source of sulfur is the Sulfur dune, which produces 1 unit of sulfur per day for its owner. Sulfur may also be scattered around the adventure map in small piles typically containing 3-6 units of sulfur per resource stack.

In Dungeon towns, you can build a Resource Silo which will produce 1 unit of sulfur per day for the kingdom.

Calid the Heretic is able to produce 1 additional unit of sulfur per day for the Kingdom he serves. Also, any hero equipped with the Eversmoking Ring of Sulfur produces 1 unit of sulfur per day (Calid would produce 2).