Crimson Tide

A wave of crimson tendrils lash out and all enemies within 25ft must make a Con save. On a success they take 3d6 necrotic damage and on a fail they take 6d6 necrotic damage and are marked with contagion. while a creature is marked with contagion, they are poisoned, slowed by 5ft, and they take 1d6 necrotic damage whenever they are damaged by a spell or an attack. This lasts for 1 minute or until it dies. Any healing removes the effect and heals for 1d4 less.

at higher levels: for every level above 4 that this is cast at, it does an additional 1d6 damage and has 5ft bonus range.