Andor 

"I hope you got this right, little one, we probably won't get another chance." Andor jogs East (L5) and launches a lightning bolt to fly at the height to hit a human in the gut passing directly underneath the Tressym.

"Carrow, if he loses the spell puts some holes in him please." 

Casts Lightning Bolt for 25 

Andor calls forth another bolt of lightning, and dazzling light once again crackles across the clearing. When the light fades, the Zhent mage can be seen weakly kneeling on one knee. Barely able to avoid the deadly full force of Andor's attack, the mage conjures his own bit of light that streaks toward Andor and Carrow and then fills the area with an explosion of flame (27 fire damage, halved with a successful DC 14 DEX save).

DEX saves: Andor 17 | Carrow 18

The mage then staggers 30' eastward (to U3), trying to reach the cover provided by the nearby trees. 

The display of magical power between sorcerer and mage spurs the other Zhentarim into action. Zhent #2 says to his comrades, "Take the goliath," as he hops off his horse, turns his aim on Rixton, and fires...

• Light crossbow attack: 21 | Piercing damage: 8

Xolkin and the other Zhent (#1) remain on their horses and draw their scimitars. That is the only action that Xolkin takes, however. He remains where he is as Zhent 1 spurs his horse forward so he can swing his scimitar at Vigan...

• Scimitar attack 1: 25 | Piercing damage: 8
• Scimitar attack 2: 7 | Piercing damage: 7

 (Actions for Carrow, Ladrian, Rixton, and Vigan are next)

Rixton:

"Ladrian, keep your eye on Larg!" I say, then dart forward, eyeing the Zhentarim (#2) that decided to fire on me, looking for a weakness in his defenses.

Bonus action - Insightful fighting: 7

Short sword (+1) Attack: 25 Damage: 10

If the Zhent fails its deception check, add 12 to damage.

Deception for Zhent 2: 10

 Vigan (Work in Progress)

Dodging the first attack, the goliath stands up in his stirrups to both block the second attack and unbalance the Zhentarim (#1) enough that an opening appears for him to retaliate with a flurry of blows.

Riposte Attack: 21

Riposte Damage: 10

Attack 1: 12

Damage 1: 13

Attack 2: 14

Damage 2: 8

Polearm Master Attack: 23

Polearm Master Damage: Polearm Master: 8

Carrow 

"Andor, Andor, are you alright ?" The Ranger seeing his friend hurt again begins to boil with frustration, a frustration that soon turns to anger as the mage manifests in the clearing and tries to stagger to safety. On foot now the half orc tracks his prey, steadies his breath and shoots.

Bonus Action: Slayers Prey 

Attack: 14 

Damage: 11

Slayers Prey: 8

Attack2: 10 

Damage: 4

Edit:

Crit 2 

Savage Attacks 6

In vain, the Zhent mage tries to reach the safety provided by the forest, for Carrow's aim is deadly. His first arrow pierces the mage between the shoulder blades, killing him instantly. Before his lifeless body can fall to the ground, a second arrow pierces him in nearly the same place as the first one. 

Zhent #1 pays a high price for charging Vigan. The goliath swings his glaive with merciless accuracy, striking the Zhent four times in quick succession. With deep wounds opening and streaming blood, the Zhent, remarkably, remains upright with blade drawn and resolved to continue the fight.

(Ladrian's action is next; Andor will then follow, beginning the next round)

(Posting action for Ladrian)

Nodding in response to Rixton, Ladrian urges his horse forward a short distance to ensure that he's close enough to Larg to prevent the dwarf from making an escape. He then lifts his crossbow and fires a shot at Zhent 2, who is engaged in melee with Rixton...

• Light crossbow attack: 14 | Piercing damage: 7 + 5 sneak attack damage, if successful

Ladrian's shot is a narrow miss. 

(Andor's action is next; to be followed by the Zhentarim)

Updated map: 

Andor 

"Just showing off now aren't you, still, good job my friend." He says to Carrow while kneeling after the fireball attack nearly killed him, his clothes smouldering Andor looks wiped out. Then a mischievous grin comes over his face as he stands up. "Can't let you have all the fun and Vigan really hates this" he adds with a wink before setting off towards the meele to the south.

As he moves Carrow can see storm energy flying around him as he shapes his energy reserves into another devastating spell. Bracing himself he throws out a third lightning bolt this one striking the first, Zhent engaged with Vigan before hitting Xolkin as he stands back from the fight.

Movement to M5

Bonus action converts 5 sorcery points into Level 3 slot

Action Casts Lightning Bolt for 28 lightning damage. The spell is aimed to strike Zhent 1 and Xolkin without hitting Vigan. 

Andor summons a bolt of lightning for yet a third time. Zhent 1 is quite literally sent flying off his horse; he lands with a thud in front of Xolkin, and his body is strangely contorted and lifeless. The riderless horse then bolts past Vigan and westward across the road. After supplanting Vigan's foe, the lightning bolt continues on and strikes Xolkin as well. He is able to maneuver himself in such a way to avoid taking the full force of the sorcerer's spell, but he is wounded nonetheless. 

Vigan, who is very nearly engulfed in blistering heat and deadly electricity, is blinded temporarily by the intense light; his horse, panicked, begins to move erratically and resist his commands. 

Zhent 2 draws a dagger with his left hand to join the scimitar he wields in his right. He continues his assault on Rixton with both blades...

• Scimitar attack 1: 6 | Slashing damage: 9
• Scimitar attack 2: 24 | Slashing damage: 5
• Dagger attack 1: 17 | Piercing damage: 6

Xolkin shakes off being struck by Andor's lightning bolt and spurs his horse toward Ladrian. Also drawing a dagger with his left hand, Xolkin descends upon Ladrian and makes his three attacks...

• Scimitar attack 1: 22 | Slashing damage: 6
• Scimitar attack 2: 8 | Slashing damage: 7
• Dagger attack 1: 13 | Piercing damage: 5

Tracking:

• Xolkin is engaged in melee with Ladrian (top of M17)
• Zhent 2 is engaged in melee with Rixton (middle of R16)
• Riderless horse is running west and located in (I13)
• Larg has not moved (P18)

(Actions for Carrow, Ladrian, Rixton, and Vigan are next; Vigan must make a successful DC 15 animal handling check or lose his action)

Vigan

The the smell of ozone fills the air around Vigan, with the air almost seeming to take on a bluish tinge as a stream of profanities in the common and giant languages explode from the fighter.  He attempts to bring his startled horse under control, and with some effort, gets it to stop before it bolts into the trees.

Animal Handling: 11

Rixton:

I dodge the first swing but the Zhentarim is fast. I am truck rapidly twice in a row by his sword and dagger. I grip my sword tightly. I can't end this fight fast enough and Vigan is darting off in the wrong direction. Very well. Time to change things up. I strike the Zhentarim's sword wielding hand at the wrist with the butt of my short sword in an attempt to knock his scimitar from his hand.

Disarm Attack: 24 Damage: 0

The strike feels true and before I can see whether or not he is able to hold on, I follow it up with a swift punch at his throat.

Bonus unarmed Attack: 7 Damage: 4

 The Zhent's right hand goes numb instantly and his scimitar falls harmlessly to the ground. Wise enough, however, to keep his eyes on his foe, the Zhent moves his body to the right, causing Rixton to miss with his martial arts strike. 

(Actions for Carrow and Ladrian are next)

Carrow 

Static electricity and the smell of burning occupy the air around the ranger as he watches Andor. Lightening arcs between himself and the Zhentarim in a bright flash.

Unable to keep a straight face Carrows tusks begin show as he barks out a harsh laugh. Within the swirling melee he watches as Vigans mount begins to bolt under a barrage of harsh language. 

"Well isn't that a sight" still laughing at the big man struggling to stay on his horse he notices Rixton has been engaged in hand to hand combat. "Give Xolkin another blast, the big man won't like you stealing his fun"

Walk south 30m, Attack Zhent 2

Attack: 23 

Damage: 5 

Attack2: 10 

Damage: 10 

Ladrian

With Xolkin close he draws his rapier and tries to hit Xolkin

Attack: 15 Damage: 7

As a bonus action he provides Help to Rixton, due to Master of Tactics, for his next attack

Carrow, seeking to aide Rixton, stings Zhent 2 with his first arrow, but the ranger's second shot is wide to the left and the arrow skitters through the trees. Ladrian, fighting off Xolkin, thrusts his rapier at his foe, catching him with a grazing blow on the arm.

(Round concluded. It is now Andor's turn to act, beginning the next round; actions for Xolkin and Zhent 2 will follow)

Updated map (orange diamond in I13 represents a riderless horse): 

Andor 

Too far away to cast anything useful the sorcerer runs as fast as his wounds allow South towards Xolkin, trusting in Vigan and Rixton to finish off the other Zhent.

"Shit, shit, shit, shit shit. Come on Andor keep moving, keep moving."

Movement to N11

Recognizing the futility of fighting with nothing more than a dagger, Zhent 2 slides from his saddle to retrieve his scimitar from the snow-covered ground. He then takes a few steps toward the tree and turns around so he can have both Rixton and Vigan within his sight.

His confidence rising, Xolkin grins wickedly at Ladrian before hacking at him with his scimitar and dagger...

• Scimitar attack 1: 24 | Slashing damage: 8
• Scimitar attack 2: 18 | Slashing damage: 9
• Dagger attack: 10 | Piercing damage: 4

(Actions for Carrow, Ladrian, Rixton, and Vigan are next)

Rixton (I think Z2 is more than 30' from Ladrian, so no advantage for me):

I slash at the Zhentarim as he picks up his sword.

Short sword (+1) Attack: 10 Damage: 7

Then I disengage (using cunning action for my bonus action) and mount his horse (using half my speed) and ride it due west for 30' (the remaining movement) to O16

Ladrian

Injured, with Xolkin attacking Ladrian casts Dissonant Whispers Save DC: 15

If successful:

 
If not: