You stab yourself into the heart and leave the blade in. You take no damage from the initial stab. An golden aura emits from you for 60 ft that heals allies.

Creatures of your choice within range heals hp using your current hp. You can distribute the hp among the creatures at your discretion. Any leftover hp is lost. After hp distribution, you fall unconscious at 0 hp and do not need to make death saving throws. You can not be healed until the dagger used for the spell is removed with a DC 25 Strength saving throw or a Dispel Magic.

If you die while the dagger is still inside your heart or 3 attempts are made to remove the dagger, your soul is trapped within the dagger and your body turns to ash. 

If the dagger is removed, you must make a Constitution saving throw against your own DC. On a failure, you lose 2 saving throws and start making death saving throws, on a save, you become stabilized at 0 hp.