The Ashenheart Certainty

You pull from multiple strings of Fate at once, truncating the futures into a single, perfectly predictable model. Choose up to two willing creatures of your choice, alongside yourself, within the range of the spell. For the duration of the spell, once per round, they may choose to replace the roll of a d20 test they make with a 10. The replacement must be specified before the roll is made.

When you cast this spell using a spell slot of 7th level or higher, the replaced roll value increases by 1 for each slot level above 6th.