The Ghost Wizards are a group of 7 Wizards who attempted to kill Dracula. They were all killed by him and then, as ghost, cursed into servitutde. They each only possess 3 spells, but each Ghost Wizard has a different set of spells and Dracula can grant them access to a 4th spell.
The Ghost Wizards are mostly quite reasonable and are decent beings.
They are formidable opponents with mighty magic and are remarkably resilient for ghosts, but can still be damaged with holy-edged weaponry and presumably some ninja powers.