Grand Impact

On a critical hit your opponent must make a a DC 10+Prof.Bonus+(Str or Con modifier) saving throw. On a failed save the opponent is sent 10ft away and knocked prone. On a successful save the opponent is knocked back 5ft.

You gain a +2 to either Strength or Constitution 

*The saving throw can be the between the option of Strength or Constitution. Picking one of those will say what the saving throw will be.