Descend into Darkness

The whispers of the Shadow Demon fill your mind, bidding you to give into the darkness in exchange for strength. Your form is consumed by darkness as your shadow draws into yourself leaving no shadow behind, your eyes turn and glow a ice blue color. You temporarily gain Sunlight Sensitivity, and bright light negates bonuses of this spell. You must make a Constitution saving throw upon activation of this spell (DC 12).

Upon success you are granted Advantage on all spell attacks for the duration. You also gain +10 temporary hit points for the duration of the spell, and +5 damage to cold damage in addition to maintaining control of yourself.

 Upon failure you fail to maintain control of yourself and submit to the will of the Shadow Demon in addition to gaining all the benefits of Descend into Darkness.