D&D Combo: Elven Fighter: Battlemaster with Elven Accuracy, Crossbow Expert and Sharpshooter. Uses Commander’s Strike to give Rogue Mastermind the chance to use it’s Sneak Attack as a reaction. Rogue: Mastermind makes another Sneak Attack on its turn. Uses Bonus Action to… Give Advantage to the Battlemaster. The Battlemaster takes a -5 to hit in order to deal an additional 15 points of damage. Elven Accuracy gives it an additional D20 to roll along with already having advantage. Rinse and Repeat. Massive crossbow damage. Double sneak attacks.

— Todd Kenreck (@ToddKenreck) November 13, 2020

Want to do this at range? Battlemaster uses Distracting Strike to give the Rogue advantage on the next attack. Give that Rogue Elven Accuracy and you've got a 14 percent chance at a crit on sneak attack.

— Todd Kenreck (@ToddKenreck) November 13, 2020