Shield Bash Master

When you use the shield bash feat and deal damage you also push the target 5 feet in a direction of your choosing. If you score a critical hit on your shield bash you may push the target 10 feet instead. 

The creature being pushed may make a strength saving throw DC 8 + Strength + Proficiency bonus, on a successful roll they are not pushed back, of the hit was a critical than reduce the push to 5 feet instead.