Please use map coordinates when describing any movement.
Cato, re-roll your attacks since you have advantage. No need to re-roll damage unless you crit on one of them.
Attack 1 - (1d20+5)
(18) + 5 = 23
Attack 1 (Advantage) - (1d20+5)
(3) + 5 = 8
Attack 1 Damage - (1d8+4, 1d6+15)
1d8+4 : (2) + 4 = 6
1d6+15 : (5) + 15 = 20
Attack 2 - (1d20+5)
(18) + 5 = 23
Attack 2 (Advantage) - (1d20+5)
(2) + 5 = 7
Attack 2 Damage - (1d8+4, 1d6+15)
1d8+4 : (7) + 4 = 11
1d6+15 : (1) + 15 = 16
Colossus Slayer Extra Damage - (1d8)
(3) = 3
Attack 1 Base Damage - (1d8+15)
(5) + 15 = 20
Attack 1 Extra Damage - (4d6)
(6123) = 12
Attack 2 Base Damage - (1d8+15)
(7) + 15 = 22
Attack 2 Extra Damage - (4d6)
(4512) = 12
Troll Bite - (1d20+11)
(1) + 11 = 12
Troll Claw 1 - (1d20+11)
(19) + 11 = 30
Troll Claw 2 - (1d20+11)
(9) + 11 = 20
Troll Claw 3 - (1d20+11)
(19) + 11 = 30
Troll Claw 4 - (1d20+11)
(11) + 11 = 22
Jabolins! - (1d20+7)
(10) + 7 = 17
Jabolins! - (1d20+7)
(15) + 7 = 22
Jabolins! - (1d20+7)
(5) + 7 = 12
Jabolins! - (1d20+7)
(17) + 7 = 24
Troll Claw Damage 1 - (3d6+6)
(135) + 6 = 15
Troll Claw Damage 2 - (3d6+6)
(654) + 6 = 21
Troll Claw Damage 3 - (3d6+6)
(336) + 6 = 18
Troll Claw Damage 4 - (3d6+6)
(615) + 6 = 18
Attack 1 - (1d20+6)
(9) + 6 = 15
Attack 1 (Adv.) - (1d20+6)
(8) + 6 = 14
Attack 2 - (1d20+6)
(16) + 6 = 22
Attack 2 (Adv.) - (1d20+6)
(9) + 6 = 15
Damage (Attack 1) [Slash+Cold] - (3d6+3)
(636) + 3 = 18
Damage (Attack 2) [Slash+Cold] - (3d6+3)
(615) + 3 = 15
Divine Smite 1 [Radiant] - (3d8)
(417) = 12
Divine Smite 2 [Radiant] - (3d8)
(661) = 13
Great Weapon Fighting (Attack 2) - (1d6, RA)
(5) = 5
Savage Attacker (Attack 2) - (3d6+3)
(362) + 3 = 14
Lightning Damage - (8d6)
(24533461) = 28
Troll Save Versus Lightning - (1d20+2)
(1) + 2 = 3
Attack 1 - (1d20+5)
(5) + 5 = 10
Attack 1 (Advantage) - (1d20+5)
(14) + 5 = 19
Attack 1 Base Damage - (1d8+15)
(4) + 15 = 19
Attack 1 Extra Damage - (4d6)
(1244) = 11
Attack 2 - (1d20+5)
(1) + 5 = 6
Attack 2 Advantage - (1d20+5)
(3) + 5 = 8
Attack 2 Base Damage - (1d8+15)
(2) + 15 = 17
Attack 2 Extra Damage - (4d6)
(3131) = 8
Colossus Slayer Extra Damage - (1d8)
(3) = 3