After resistance, Ug takes 12 piercing damage. He is also poisoned, and can't regain hit points until the poison is cured, though he might still pass his other Con save to stay up. However, he takes another 23 poison damage at the start of this coming turn...
Al takes 15
Vince takes 38 and is knocked unconscious, unless he casts Shield
Ras takes 27
Rolls
Merodach vs Ug (adv), and Al, Vince, Ras (1 attack each) - (2d20+14, 1d20+14, 1d20+14, 1d20+14)
2d20+14 : (23) + 14 = 19
1d20+14 : (6) + 14 = 20
1d20+14 : (4) + 14 = 18
1d20+14 : (19) + 14 = 33
dmg to Ug (piercing) - (4d6+8)
(1646) + 8 = 25
Ug con save DC 21 vs poison - (1d20+8)
(1) + 8 = 9
dmg to Al - (2d8+8)
(52) + 8 = 15
dmg to Vince (unless Shield) (bludgeoning, fire) - (2d6+8, 6d6)
2d6+8 : (53) + 8 = 16
6d6 : (226255) = 22
dmg to Ras - (3d10+8)
(199) + 8 = 27
dmg to Ug (poison) - (6d6)
(616433) = 23