Critical Momentum

You touch a creature and increase its lethal potentiality. The targets attacks score a critical hit on a roll of 19 or 20 for the duration.

At Higher Levels. When you cast this spell using a spell slot of 4th or 5th level, the spells duration increases to 1 hour. When you use a spell slot of 6th or 7th level or higher, the spells duration increases to 8 hours. When you use a spell slot of 8th level or higher, the targets attacks score a critical hit on a roll of 18 or 20.