The magical girls used their Soul Gems to defeat the witches. When they overused their Soul Gems, their Soul Gems turned into Grief Seeds causing them to either become the witches or end up dead.
The Mankai Heroes are those magical girls in Yuki Yuna is a Hero where they performed a Mankai sacrificing their body parts for the Divine Tree (Shinju-sama). If they overused their Mankai powers, they end up dead after fighting the vertexes.
Both these series are based on the magical girls fighting for their causes either against the witches or the vertexes using either the Soul Gems or performing the Mankai or the Sange (Yuusha System). In Magia Record or Mahou Shoujo Madoka Magica, the magical girls lose their lives or become witches after their Soul Gems turned into Grief Seeds. But in Yuki Yuna is a Hero, the heroes performed the Mankai or activate Sange fighting the vertexes but when they overused their powers, they end up dead unable to move their bodies.