onMinigameHealth would be an event that detects a player's health (similar to onMinigameDeath) and if it is above, below or at a certain health level it would do the event.
Like:
[onMinigameHealth] (number) (above boolean) (below boolean) > [Player]/[Minigame]/[Client] > [whatever you want it to do]
Or: (V combining both will make it detect if it's at a specific level)
[onMinigameHealth] (50) (X) (X) > [Client] > [centerPrint] (Your health is at 50%!)