You form a noxious cloud of corrosion at any point in the spell's range. The cloud then will travel forward 5 feet a round, until you lose concentration or the duration ends. Each creature that touches the cloud must make a Constitution saving throw. Each creature that succeeds this save takes 1d4 poison damage each round for 4 rounds, and has their AC and Spell Save DC reduced by 2 for 4 rounds. Each creature that fails this save takes 1d6 poison damage each round for 4 rounds, and has their AC and Spell Save DC reduced by 4 for 4 rounds. 

At the beginning of each creatures turn, that creature can make a Constitution saving throw. Succeeding this save will end the effect of this spell on that creature immediately, but it can be reapplied by touching the cloud again. 

This spell’s AC and Spell Save DC decrease increases by 2 when cast as 7th level spell, 4 as a 8th level spell, and 6 as a 9th level spell.