Trickster's Mark

The trickster selects one creature within sight.  That creature is marked for the duration of the spell, or until it dies.  For the duration of the spell, the trickster has advantage on attack rolls against the marked creature.  If the creature dies before the end of the spell, the trickster can use a reaction to transfer the mark to another target, with the duration resetting.  If there are no other creatures in range when a target dies, the trickster can hold the spell in concentration until taking a long rest.