You infuse a vital surge of life into up to 4 creatures of your choice within range. Once during the duration of the spell, they can trigger this vital surge as a bonus action, regaining 4d8 hit points. When they trigger this surge, they can expend up to a number of hit dice equal to half the level of the spell slot used to cast this spell, rolling them as they normally would and adding the amount of hit points restored to the effect of this surge.
Once a creature triggers this healing surge, the spell ends for that creature.