Beholder

Beholder mobs are probably the most devastating Undead mobs in BlockWorld. Their upper pair of smaller eyes deal heat, cold, poison and necrotic damage to everything within range, while the single smaller eye can wield staffs that enable magic attacks. Beholder presets also feature some devastating items, like Incineration Staff. On the up side, defeating a beholder will grant much experience and money and there is a good chance to acquire one of their items. Beholders can be quite devastating for someone unprepared, but they don't have any special defense against any type of damage and the few LUP they gain donnot allow for withstanding much damage (their insane Breath makes air and health regeneration incredibly fast though).