Watch: 'Boston Three Party' gives Celtics commanding halftime lead

Pritchard did the same thing to end the third quarter in Game 2, giving the Celtics a nine-point cushion that they'd end up needing down the stretch. This make gave Boston a 21-point lead and delivered a gut punch to a Mavericks team facing elimination.

Boston has gone 10-for-21 from three-point range while building a 21-point halftime lead, going into the break leading 67-46. Dallas has made a stronger effort in Monday's Game 5, but it's only gone 6-for-19 from deep. 

Part of the Celtics' dominance came from the stellar passing of Jayson Tatum, who had nine assists in the first half.

Even with all his generous passing, Tatum still wanted to get in on what ESPN's Mike Breen called a "Boston Three Party." He made his first three of the game to give him a game-high 16 points with a cold-blooded side-step jumper from 27 feet.

Boston is 24 minutes away from an NBA title, and its three-point barrage is a huge reason why the team is within striking range.