House Tza'dorin is a shady drow mercantile House based out of the Underdark city of Mithuth. The organization was founded within the belly of the Paradise Isles, and has continued to thrive thanks to their ties to the greater Underdark and mastery of drug and poison crafting. While claiming neutrality and lack of a central deity, the city they've constructed seems to speak strongly of dark intent. The members are elusive, and membership is utterly exclusive.

The House and the city of Mithuth which it is inextricably tied to are officially part of the Kingdom of Haven, but the Kingdom itself exercises no force upon either and the House itself denies this truth altogether.