You touch a creature within range and mark it with an elemental rune. Choose a spell you know or have prepared that deals acid, cold, fire, lightning, thunder or poison damage, and is of a level equal to or lower than the spell slot expended to cast this spell.   The creature can cast the spell without expending a spell slot, using your spellcasting modifier. Once the spell is successfully cast, the rune fades and this spell ends. Until this spell ends, you cannot regain the spell slot expended to cast this spell.