We finished this campaign a couple weeks ago in the middle of lvl 19. Nobody had anything significant left to get at lvl 20 since we'd all multi-classed.
During the last battle as a 15th Monk (Way of Four Elements) / 4th fighter (Battle Master) rocking a Growth potion and a Hunter's Mark (from a tattoo) I did 204 points of electrical damage in the second round.
Attack (doubled with Action Surge, w/ a critical hit)
5D10+28
5D10 (Fangs of Fire Snake damage for 4 Ki)
5D4 (Growth)
5D6 (Hunter's Mark)
5D8 (Superiority Dice)
Bonus Action Fury of Blows
2D10+14
2D10 (Fangs of Fire Snake damage for 2 Ki)
2D4 (Growth)
2D6 (Hunter's Mark)
Total
14D10 + 5D8 + 7D6 + 7D4 + 42
This coming Sunday we start anew in the world of the Wheel of Time. I made an Accepted from the White Tower. The others are a fighter, a bard and two Artificers (fireworks and clockwork). I can't wait.