Curse is a power that enables its user to inflict their targets with various kinds of ailments, making it possible to defeat enemies without having to resort to violence.
Jubaku Ensa「呪縛怨鎖, Jubaku Ensa; literally meaning "Binding Resentment Chains"」: The spell summons chains made out of darkness in order to trap an opponent with them. Those who are trapped by the chains, are cursed and unable to leave the location they currently are in. Gilfrost commented that there is an incredible amount of power behind them.
Five Lost「五識是空, Faibu Rosuto」: A spell that creates a magical orb that causes the victim to lose all five of their senses upon contact.
Breakable Bug「五分の魂群, Bureikaburu Bagu」: A spell that summons a swarm of insects. The full effect of this spell was not shown as Merlin stopped the attack before it was able to connect, though it's likely meant purely to capitalize on Grayroad's Commandment by sending easily disposable minions that the enemy can destroy, thus triggering the Commandment.