One of players has taken the Battle Hymn Song of Clarity. On the surface these seem obvious, but then it gets complex.
- Song of Clarity: Choose one creature within 60 feet. At the start of its turn, the chosen creature may expend and roll one of its hit dice to regain hit points.
- Battle Hymn: At the start of your turn, you can activate a battle hymn by expending a use of Bardic Inspiration (no action is required). Performing a battle hymn requires your concentration, as though you were casting a spell. Once activated, a battle hymn continues until you choose to end it or lose concentration, or if activated during a combat whenever the combat ends.
- Let the same person spend a HD at the start of every round?
- Choose a different person to do this every round?
- Sing it once, ignoring all that stuff about concentration and continuing the song?