Great Sword = 2d6 + 5
Great Weapon Master Feat = + 10
Lvl 5 Oath of Vengeance Paladin‘s Divine Smite = 5d8 and Branding Smite = 2d6
Lvl 8 War Domain Cleric‘s adds more spells slots for more divine smites and it’s Divine Strike = 1d8
Lvl 3 Battle Master Fighter grants Action Surge to 2 more attacks and Superiority Dice = 4d8
Lvl 3 Hunter Ranger gives Colossus Slayer = 1d8
Lvl 1 Rogue for sneak attack = 1d6
Across 4 attacks with action surge that translates to: 17d6 + 27d8 + 60!!!
Attack 1 of 4 with action surge
(5d6 + 11d8 + 15) = Max damage 133
Attack 2 of 4
(4d6 + 6d8 + 15) = Max damage 87
Attack 3 of 4
(4d6 + 5d8 + 15) = Max damage 79
Attack 4 of 4
(4d6 + 5d8 + 15) = Max damage 79
Total for 1 turn = 378