The drow lunges forward and attacks Zera in desperation at being seen in the act:

attack 1: 25 damage: 5

attack 2: 16 damage: 8

Init order:

Zera -> Amotal -> Friar -> Veil -> Drow

The first hit hurts her, and she responds by hexing him and shooting a blast of eldritch energy from her hand.. (post above) 

edit-  actually both hit-  she is at 3 HP-  doesn’t change her actions above.

While the hex envelops the drow, he does manage to get his shield up in time to deflect the eldritch blast harmlessly into the wall opposite him in the alley.

Amotal flies forward, his shortswords coming off his belt and flying at the dark elf. He aims not to kill, but still applies as much force as he can. The eladrin is unarmored, having left his armor at home that morning.

Attack: 13 Damage: 3

Attack: 10 Damage: 7

Veil growls low in ehr throat as her tail twitches in agitation. Seeing the head roll ont he ground, she lifts a hand. Calling on her chaotic magic, she sends a blast of flame at the drow.

Using Tides of Chaos to get advantage...

fire bolt

Attack: 23 Damage: 6

Amotal's first strike is deflected with a sneer from the drow "Another filthy elf!"

The second evades the drows defenses and cuts the drow who only growls at the wound.

The Friar notices the renewed focus of this foe toward Amotal. He prays "Ilmater protect him and bless them!"

Veil, Zera and Amotal are blessed. 

A shimmering red dome enshrouds Amotal as a sanctuary  

((The bless adds +4 to Veil's attack - which makes it break the drow's AC))

Veil's firebolt whizzes down the alley and slams into the drow. He seethes in anger.

A glower passes over the drows face

Wisdom save vs sanctuary: 9

He approaches Amotal with bloodlust in his eyes, but suddenly he closes his eyes and shakes his head, as if a bright light had been blasted into his mind. He scoffs in disgust, and steps back further into the shadowy alley.

Zera -> Amotal -> Friar -> Veil -> Drow

Zera again shoots a bolt of crackling energy at the drow:  19 plus 1 bless to hit;   6 force damage plus 6 necrotic damage if hit(hex)   She then backs away a little to be further from range, and says a (BA) word of healing 7 on herself.

The drow winces with the necrotic damage. He is wounded, but still appears to have a good deal of stamina to him.

Amotal -> Friar -> Veil -> Drow -> Zera

Amotal speaks a word in sylvan and a faint outline of mist encircles the drow. He swings one of the blades again.

Attack: 27 Damage: 18

(Whew. Thought that was a nat 1 for a minute.)

At Amotal's attack, thered veil of sanctuary dissipates around him. His attack flies wide, but the connection of the misty outline remains as a bond between hunter and quarry.

Friar Xavier rushes forward to Zera, checking to see how she is. He calls out "Repent! Murderer of brothers and sisters!" to the drow. He prepares to Help his companions in any way they may need.

Veil -> Drow -> Zera -> Amotal -> Friar

Vale sends another blast of flames at the drow...

fire bolt

Attack: 7 Damage: 10

The bolt again whizzes by the drow. He grimaces and charges at Amotal with his shortsword:

attack 1: 9 damage: 8

attack 2: 13 damage: 6

Zera -> Amotal -> Friar -> Veil -> Drow

“Yield and we will let you live” zera says, but she shoots at him again.

11 to hit, 4 force damage plus 2 necrotic if hit.

Again, he easily deflects the blast with his shield. "Oh, I am not worried elf-lover. You should be."

((puppeteering Amotal as a few days have passed))

Amotal pulls out his second shortsword with a flourish and attacks:

Attack: 13 Damage: 11

Off-hand Attack: 20 Damage: 7

The Drow staggers backward under the ranger's flashing blades.

Friar Xavier sighs and prays that Ilmater's purifying power, may burn out the hatred in the drow.

Drow Dex Save: 16

A flash of divine power descends toward the drow, however, he spins and places himself out of its reach in the very last second.

Veil  -> Drow -> Zera -> Amotal -> Friar

Veil sends another blast of flame at the drow...

fire bolt

Attack: 9 Damage: 1

The drow laughs, and begins to align his blade for his next attack, when all in the alley hear the sound of approaching marching feet. The City Watch approaches!

His laugh turns to a sneer as places his sword under his arm and draws something from a pouch at his waist. His lips mouth a word as he scatters some black powder. A 15 foot field of darkness forms just behind him as he retreats into it, disappearing.

The watch enters the alley just after he disappears. They see the dead sailor and some of your drawn weapons and immediately call out: "Halt! Drop your weapons!"