All enemies within range have mana sucked from them and given to you. Artifact belonging to the original Order of the Dungeon Mages, started by the Constructor himself. Made of the skulls of the most talented mages after their demise. To a Dark Caster, this is a great honour.
The Oceanic Core is a Pre-Hardmodeaccessory dropped by Dark Casters and Dungeon Overseers that increases the players mana regeneration based on the amount of nearby enemies.