You enter into a mystical meditation. While you are casting the spell (during 5 minute, or more if you cast it as a ritual), you are blinded, but have advantage on all Wisdom check (Perception) that rely on an another sens (hearing, smell...) and are under the effect of the Detect magic spell. Plus, the effect of this meditation gives you an your absolute tranquility that allows you to heal yourself. When you finally cast the spell, you can spend hit dice to heal yourself. When you do so, you can use your spell casting modifier instead of your Constitution modifier.