As an action, sunlight bursts from you. Each creature other than you in a sphere centered on you must make a Fortitude saving throw.
On a failure, it takes 1d8 radiant damage and is blinded until the end of its next turn.
On a critical failure, it takes twice as much damage.
On a success, it takes half as much damage.
On a critical success, it takes no damage.
You can increase the damage by 1d8 for each additional mana expended.
You can expend 2 additional mana so it deals no damage, but the sunlight continuously radiates from you. The duration changes to 1 minute/mana, concentration and the sunlight radiates from you in an aura shaped as a sphere. Until the spell ends, the aura moves with you, centered on you.
You can expend 1 additional mana if the sunlight continuously radiates from you, so the corona hedges out undead creatures. The corona prevents an affected creature from passing or reaching through. An affected creature can cast spells or make attacks with ranged or reach weapons through the corona.
If you move so that an affected creature is forced to pass through the corona, the spell ends.