Vacum

Sucks the oxygen out of a five foot cube within the casters sight. Creatures within the spell must make a Constitution save vs spell save or have the air expelled from their lungs and take 2d6 suffocation damage

any creature starting their turn inside the effected area must make a DC 12 ascending by 2 per round or fall unconscious. 
remaining inside the effected area while unconscious will begin death saves.