Crippling Radiance

Bright light spreads within a 30-foot-radius centered on a point you choose within range. The light spreads around corners and lasts until the spell ends. When a creature moves into the spell's area for the first time on a turn or starts its turn there, that creature must succeed on a Constitution saving throw or take 6d6 radiant damage, its speed is halved, it can't take reactions and emits a dim light in a 5-foot radius. The light makes it impossible for creatures to benefit from being invisible. The light and other conditions caused by this spell go away when the spell ends. 

If the creature succeeds on a saving throw, it takes half the damage without further effects.