Arcane Collapse

When a spell that covers an area larger than a 5 foot space is cast or encountered, this spell may be cast upon that spell as a reaction. 

The target spell is compressed into a 5 foot diameter sphere and only affects that area. If the target spell would deal half damage or no damage, except via resistances, it deals full damage instead. Saves that would resist the target spell's effects are rolled at a disadvantage. 

If an entity is Huge or larger, or it covers more than a 5 foot by 5 foot area, and the entity is inside of the target spell's original area of effect, the entity or object is dealt 1d8 force damage, and the other effects of this spell are canceled.