Ormus - Diablo Wiki

Ormus gives a couple of quests and quest rewards, and in D2X he is the most popular NPC merchant in Act Three, simply because he is the closest to the waypoint and town portal locations, and thus the most convenient to trade with. His wares are less popular to purchase, but he is the classic magical potion seller, and his inventory includes a few types of armor, along with staves, wands, scepters, scroll and tomes, and mana and health potions.