Mordenkainen's Sword is a spell from the Dungeons & Dragons role-playing game, specifically designed for spellcasters. It creates a magical sword that hovers in the air and can attack enemies on behalf of the caster. The sword is considered a conjuration spell and is known for its ability to deal force damage, making it effective against various types of foes. When cast, the sword can strike at a target within range, allowing the caster to focus on other actions during combat. The spell lasts for a duration, and the caster can control the sword's movements, making it a versatile tool in battles.