Inferno Orbs are the large ammo type used in Heretic's Phoenix Rod. They provide the player with 10 shots (15 on skills 1 and 5).

Heretic Items Health Crystal Vial Quartz Flask Mystic Urn Armor Silver Shield Enchanted Shield Weapons Staff Elven Wand Gauntlets of the Necromancer Ethereal Crossbow Dragon Claw Hellstaff Phoenix Rod Firemace Ammo Wand Crystal Ethereal Arrows Claw Orb Lesser Runes Flame Orb Mace Spheres Crystal Geode Quiver of Ethereal Arrows Energy Orb Greater Runes Inferno Orb Pile of Mace Spheres Items Crystal Vial Map Scroll Bag of Holding Ammo Keys Artifacts Chaos Device Morph Ovum Mystic Urn Quartz Flask Ring of Invincibility Shadowsphere Timebomb of the Ancients Tome of Power Torch Wings of Wrath