[2020] Boss's regaining health during battle

Hi @Freyja1014, this is an intentional part of the leashing mechanic that was introduced to prevent players from infinitely kiting enemies.

If you believe you might have stumbled upon an issue with this please share further details regarding what actions lead to the event, such as how far the creature was from its original spawn point and if it was trying to engage a target that was out of reach.