The Great Expanse

The caster raises both arms, drawing huge black chains up from the earth in violent eruptions, the chains surge towards all targets, dealing 4d8 bludgeoning damage on impact and immobilising them. The chains then tighten, dealing 6d10 necrotic damage. Each round the targets make a strength save (DC 15) to break the chains, success frees them and failure means they take another 6d10 necrotic damage. This persists until the target breaks their chains with the strength save (DC 15)