Andor 

Moving up to Vigan Andor and his duplicates all look a little white in the face as the arrow wound rakes it's toll. "Time to go and get stuck in big guy." As he says this he touches Vigan on the forearm as both of them feel a surge of speed with Andor draining off a significant art of his power to fuel the spell. After casting the storm swirls around him again and his duplicates follow him as he moves a little behind the goliath.

Casts Haste

Uses 3sp to twin the spell.

Turn 2/10 for Mirror Image 

Carrow

Seeing the action ramp up he switches aim back to the Ogre #2 and lets another arrow fly. (+1 Arrow)

Attack 1: 25 Damage: 8 Hunters mark 5  Hail of Thorns Dex 12 if failed 8

Fitting another arrow he fires again in quick succession. 

Attack 2: 11 Damage: 12 Hunters mark 2  Hail of Thorns Dex 12 if failed 7

Edit Crit: 4  Savage attacks trait 7

Edit: Crit on attack 2 5, Savage Attacks trait: 4

With deadly precision, Carrow strikes the ogre with both shots. The massive beast totters momentarily before falling over backward and crushing the catapult beneath the weight of his body. The three goblins nearby shriek in fear as they begin to run away from the fallen ogre. 

(Actions for Vigan and Ladrian are next)

Vigan

"Take down those other two ogres!  They fall, and we ease the pressure on the keep."  The goliath readies his glaive as Andor touches his arm.  Magical energy surges through him, and he charges across the valley separating his companions from the enemy army at a blinding pace, accompanied by a blood-curdling battle-cry

Ladrian

Following the heed from Vigan Ladrian switches aim to the nearest ogre and shoots

Attack: 20 Damage: 11

Vigan streaks across the open space , covering the bulk of the ground between himself and the enemy horde. Ladrian's shot strikes the ogre as another goblin prepares to climb into the catapult. 

The hobgoblins to the east continue to exchange fire with the guards on the wall. Thus far, that particular battle is little more than a stalemate; no casualties have fallen on either side. Two more hobgoblins, however, have turned their focus to their enemies on the west. In total, five of them draw arrows and fire...

• Hobgoblin 1, longbow attack on Vigan: 13 | Piercing damage: 2
• Hobgoblin 3, longbow attack on Vigan: 18 | Piercing damage: 9
• Hobgoblin 6, longbow attack on Vigan: 19 |Piercing damage: 5
• Hobgoblin 7, longbow attack on Ladrian: 7 |Piercing damage: 4
• Hobgoblin 12, longbow attack on Andor: 13 |Piercing damage: 2

Additionally, two more goblins sail through the air toward the Keep.

(All players may take their round 4 actions)

Updated map: 

 NOTE: Disregard the un-numbered black goblin (he was the one just launched by the ogre's catapult)

Vigan

Arrows start falling thick and fast as Vigan closes in on the enemy ahead.  With a roar he falls upon the goblins and hobgoblins in front of him, glaive flashing in the sunlight.

Attack 1: 14

Damage 1: 13

Attack 2: 11

Damage 2: 9

Attack 3: 12

Damage 3: 11

Action Surge Attack: 26

Action Surge Damage: 15

Precision Strike for Attack 1: add 3 to attack roll 1

Carrow

Eager to see the Vigan in battle again the ranger has to stop himself charging head long into combat. Controlling his instinct he focuses on another Ogre #1 

Switching Hunters Mark to Ogre#1

Ogre #1 Attack 15

Damage 6

Hunters Mark 4

Hail of thorns

Dex 12 if failed 6 

Attack 2 Attack 11   

Damage 4

Hunters Mark 2

Hail of thorns

Dex 12 if failed 7 

With mind-boggling speed, Vigan slices effortlessly through two goblins and two hobgoblins. Perched from atop the western hilltop, Carrow places two more arrows into the ogre, who is then pelted with the ranger's magical thorn attack.

(Andor and Ladrian's actions are next)

Andor

The mass of Andors charge directly towards the enemy moving at unnatural speed. As the three duplicates continue to dance around the real Andor the wind begins to whip up, hair streaming wildly, cloak flying in all directions the sorcerer lifts off the ground slightly as his hands become sheathed in lightning.  As he brings them together a bolt of lightning blasts out from him, aimed at the ogre thus far unharmed by the arrows and magic of Carrow. As the spell is released Andor is pushed backwards 10' further away from the enemy line with all his copies following suit.

Casts Lightning Bolt for 33 (halved on Dex DC15 save pass) aiming to hit Ogre 3 and carry on to Hobgob 9 then uses Tempestuous Magic as Bonus Action to move 10' straight back towards original start point.

round 3/10 for Mirror Image (all three copies still intact) 

round 2/10 for Haste

Ladrian

He moves a bit further to  F8 and shoots at the same ogre

Attack: 8 Damage: 9

Andor's lightning bolt scorches the ogre and completely obliterates the hobgoblin that were standing in its path. Every creature in the area is blinded momentarily by the piercing white light, and any chance of the party's being ignored by the remainder of the horde disappears. All hobgoblins and goblins abandon their assault on Xantharl's Keep as they turn to face a far more menacing foe. 

Each ogre, wounded and seeking revenge, turns and launches a goblin toward those atop the other hill...

• Ogre 1, catapult attack on Ladrian: 13 | Piercing damage: 12
• Ogre 2, catapult attack on Andor: 21 | Piercing damage: 9

The hobgoblins, knowing they cannot cover the necessary ground to draw swords, stay with their longbows for another round...

• Hobgoblin 1, longbow attack on Ladrian:  4 | Piercing damage: 5
• Hobgoblin 4, longbow attack on Carrow:  15 | Piercing damage: 4
• Hobgoblin 5, longbow attack on Vigan:  13 | Piercing damage: 5
• Hobgoblin 8, longbow attack on Vigan:  13 | Piercing damage: 5
• Hobgoblin 10, longbow attack on Vigan:  10 | Piercing damage: 8
• Hobgoblin 7, longbow attack on Andor:  7 | Piercing damage: 5
• Hobgoblin 12, longbow attack on Andor:  13 | Piercing damage: 3
• Hobgoblin 11, longbow attack on Andor:  6 | Piercing damage: 9

 All of the goblins draw their scimitars and prepare for melee attacks next round.

(Players may take their turns for round 5, in any order)

Updated map: 

edit - misread the rolls! and also I think Andor should be right in the middle of H8 (much as I would like to hide him at the back now!)

A goblin smashes through one of the illusory duplicates as an arrow whizzes past another of the fake Andors, two arrows seem destined to strike the sorcerer cleanly but his heightened speed protects him from them both, moving just in time to avoid them he ends up still flickering with lightning about his hands stunned by the power of his spell and the change in the behaviour of the monsters...

"OK Vigan, I think we have their attention now!"

Vigan

In a (very bloody) world of his own, the goliath barely hears Andor, and launches himself at the nearest ogre (#3).

Attack 1: 13

Damage 1: 8

Precision Attack 1: 21

Attack 2: 24

Damage 2: 11

Attack 3: 12

Damage 3: 13

After being victimized by a barrage of attacks from Vigan, ogre #3 staggers a few feet to his left before crashing to the ground and crushing a goblin beneath his own weight and that of the catapult.

(Round 5 actions for Andor, Carrow, and Ladrian are next)

 (Posting round 5 actions for Andor, Carrow, and Ladrian)

Andor, targeting the one hobgoblin that is within range, casts Ray of Frost at hobgoblin #1. (Ranged spell attack: 18 | Cold damage: 5)

Ladrian sets another bolt into place and fires at the one remaining ogre. (Light crossbow attack: 19 | Piercing damage: 7)

Likewise, Carrow seeks to bring down the ogre. 

• Longbow attack 1: 13 | Piercing damage: 11
• Hunter's Mark: 5
• Hail of Thorns: 10 (halved on a successful DEX save)

Seeing that his first shot, in conjunction with Ladrian's, is the death blow for the ogre, Carrow uses his second arrow in an attempt to bring down the hobgoblin closest to Vigan.

• Longbow attack 2: 24 | Piercing damage: 9
• Hunter's Mark: 5
• Hail of Thorns: 3 (halved on a successful DEX save)

The hobgoblin collapses face down on the side of the hill; Carrow's shot and the following blast of magical thorns overwhelms the creature. 

The three goblins and the three hobgoblins that are closest to the just-fallen ogre advance toward Andor. The goblins charge with scimitars drawn, ready to engage in melee next round. The hobgoblins trudge forward with longbows drawn and each fires another shot...

• Hobgoblin 1, longbow attack on Carrow: 21 | Piercing damage: 4
• Hobgoblin 4, longbow attack on Ladrian 5 | Piercing damage: 5
• Hobgoblin 5, longbow attack on Andor: 17 | Piercing damage: 8

 The goblins and hobgoblins on the southern portion of the hill close in on the goliath. Three goblins, scimitars drawn, rush in and began hacking at Vigan...

• Goblin 19, scimitar attack: 6 | Slashing damage: 4
• Goblin 24, scimitar attack: 14 | Slashing damage: 6
• Goblin 22, scimitar attack: 19 | Slashing damage: 8

Two of the hobgoblins (8, 10) draw their longswords and stride forward, preparing to be the second wave of melee attacks on Vigan, but the two hobgoblins to the south decide against drawing swords against the glaive-wielding goliath. They draw arrows and fire...

• Hobgoblin 11, longbow attack on Vigan: 5 | Piercing damage: 3
• Hobgoblin 11, longbow attack on Vigan: 16 | Piercing damage: 9

(All players, including Rixton, may act for round 6)

Updated map: 

Andor

As the last duplicate disappears after an arrow passes through it's face the sorcerer stands alone again as three goblins attempt to rush him.  With his hands held out to the side Andor dips into his reserves of energy again, trying to end two of the little monsters at the same time. As the cold energy builds the goblins see his intent just as he releases twin rays of frost at them.

1 sp to twin Ray of Frost targetting Goblins 1 and 17

Attack Gob1 14 damage 6 cold damage.

Attack Gob17 17 damage 13 cold damage.

The sorcerer uses his unnatural speed to dart back further away from them as he moves 30' towards Ladrian.

Haste round 4/10

Ladrian

He moves a bit further to  G8 and shoots at the nearest foe


Attack: 17 Damage: 2

Rixton:

I thrust my short sword into the midsection of the bugbear.

Short Sword Attack: 19 Damage: 7

(I am assuming this was enough to finish it off. If not, I will edit this to keep fighting instead of the following.)

Move, then dash (with cunning action as a bonus action) to the trees at the top of U33.

I switch my short bow with my bloodied short sword in preparation for the next round.