Choose a willing creature that you can see within range. The creature gains 15 temporary hit points, and the creature can choose to use their reaction to move up to their movement speed and perform one weapon attack. While the creature has these temporary hit points their speed is doubled and they have advantage on Dexterity Saving Throws. On subsequent turns, the caster may use a bonus action and sacrifice a hit die. The target’s temporary hitpoints are increased equal to the caster’s level, to a maximum of 15. This allows the caster to replenish the temporary hitpoints granted by this spell. The spell ends if the creature’s temporary hitpoints are reduced to 0. When the spell ends, the target's movement speed is reduced to 0 until the end of their next turn, as a wave of lethargy sweeps over them.