As an action, freezing cold spreads out from you. Each creature other than you in a sphere centered on you must make a Fortitude saving throw.
On a failure, it takes 3d6 cold damage, is immobilized, and can’t take reactions 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 2d6 for each additional mana expended.
Aura Borealis. You can expend 1 additional mana so the cold around you is continuous. The duration changes to 1 minute/mana, concentration and the cold spreads out from you in an aura shaped as a sphere. Until the spell ends, the aura moves with you, centered on you.
Whenever a creature enters the area for the first time on a turn or starts its turn there, it must make the Fortitude saving throw. The damage is reduced to 1d4 and additional augments to the damage increase the damage by 1d4 for each additional mana expended, instead of the normal increase.