Toxic Artillery

You catapult three masses of poisonous energy towards three points you can see within range. Upon impact, the energy erupts into a 10ft radius  toxic cloud.

Any creatures caught within one of the clouds on the start of their turn must make a CON saving throw. Upon failing, they take 4d12 Poison damage, or half on a success. 

The clouds dissipate after a minute, or earlier if the caster loses concentration.