Tymm will not go down the hallway until Sky does. So he will position himself in between Sky and Zombie A. Then he will try to take that zombies head

Reckless Attack: Dirty 20

Damage: 5

There's little Tez can do from his position on the other side of the corridor and inside the chamber of the ghost. He glances into the corridor to look what keeps the others from falling back he doesn't see much in the cramped space. He decides to let Hope, his nickname for the protector cannon, crawl along the wall towards Eima (max 15 feet), so that it can help bolster his friends resolve should it become necessary. 

On Sky's turn he will keep the ball of fire between himself and the zombies.

DEX 13 Save; takes 7 fire damage on a failed save, or half as much damage on a successful one.

Will Sky keeping the fire in front of himself, Eima adds her own fire in front of Tymmy.

Create Bonfire
Damage: 8 fire
DEX DC 13

[[ I'm not exactly sure where everything is right now, but hoping that create a makeshift wall of fire between our characters and the zombies. ]]

Eima's fire roasts the zombie good! (failed save!)

Tez's helpful companion starts heading to the hall!

Tymm whacks the zombie just so...but it barely manages to hold itself together, clinging to it's non-life life!

Sky continues the burning fire, embroiling the poor undead in magical flames! (Dex save fail!...but it its ghastly state it seems to still be standing!)

The zombie swipes back at Tymm through the fire! (9 to hit misses!)

OOC: Undead Fortitude is a real pain! Fire doesn't seem to be overly effective, maybe something else will!

Round 3 ready!

The blue X is the mechanical companion.

[[ In another PBP we ended up calling a zombie The Great Undying One after he made 4 or 5 successful undead fortitude saves. ]]

Still concentrating on her fire, Eima lets loose a crossbow bolt at the zombie next to Tymmy.

Bonus Action: Steady  Aim
Action: Attack

To-Hit: max(9,5) + 5 = 14
Bow Damage: 3+3 = 6 piercing
Sneak Attack Damage: 6+1 = 7 piercing
Total Damage: 13 piercing

Create Bonfire
Damage: 8 fire 
DEX DC 13

Reckless Attack: Nat 20

Damage: 10

Tymm takes another swing at Zombie A, hoping to cleave it right down the middle. After that attack he will move as far down the hallway as he can

Tez remains ready to help but stays in position, his little spidery construct continues climbing the wall all the way to the ceiling just above Eima.

(@DM I would have the Flaming Sphere right next to Zombies A,B, and C so that they all would be impacted by it. )

[Any creature that ends its turn within 5 feet of the sphere must make a Dexterity saving throw. The creature takes 2d6 fire damage on a failed save, or half as much damage on a successful one.]

Quote from GR_Mustang >>

(@DM I would have the Flaming Sphere right next to Zombies A,B, and C so that they all would be impacted by it. )

[Any creature that ends its turn within 5 feet of the sphere must make a Dexterity saving throw. The creature takes 2d6 fire damage on a failed save, or half as much damage on a successful one.]

 The zombies took damage on their turn, then moved out of the initial spot of the fire, toward the door. Sky can move the sphere as a bonus action on their turn to reposition it if they want so the zombies get hit again.

Eima's zings the zombie but it keeps itself together!

Tez's helpful companion gets into a better position!

Tymm whacks the zombie just so...and downs it for good this time!

Sky continues the burning fire, bringing it over to continue burning the zombies! (Dex save 19, 16, and 1 for 9 fire damage)

The zombies shuffle to the corridor and another one takes a swing at Tymm! (22 to hit this time, 7 bludgeoning damage)

"Oi!" says Eima as the zombie strikes Tymmy, "Keep yer hands to yourself!"

continued concetration of Create Bonfire
Damage: 1 fire
DEX DC 13

Bonus Action: Steady Aim
Action: Attack a zombie

To-Hit: max(11,6) + 5 = 16
Bow Damage: 4+3 = 7
Sneak Attack: 4+6 = 10
Total Damage: 17 piercing

Tymm’s plan of luring the zombies to the other end of the hall is great in theory. But then Tymm got hit. The pain of the blow brings him back to the first real pain he ever experienced. He remembers the bear. He remembers the biting pain of the claws on his young face. He remembers the absence of fear, and the overwhelming feeling of RAGE

Bonus Action: Bear Rage

Action: Tymm will then attack the closest Zombie still standing

Reckless Attack: 24

Damage: 4

Tez is  peeking around the corner and crunches up his face when Tymm gets hit. „Steadfast, friends. You’ve got them!“ he cries out. „Hope is near,“ he adds and sends the little helper a bit closer to Tymm (10 feet west so that he‘s within 10 feet) and activates the construct. (10 temporary HP for everyone within 10 feet who has less.)

Between flames and bolts Eima fells some more zombie scum! (failed save! good hits!)

Tez uses their companion to keep everyone shielded!

Tymm smashes into another zombie hard! (hit! looking pretty rough!)

Sky blasts it with more fire as well, making it growl! (produce flame: 20 to hit, 7 fire damage...the zombie is hanging in there though!)

The zombie in front of Tymm swings but the weak charred hand misses...hand...ily...ha! (6 to hit misses!)

Tymm will just keep doing what works. Swinging notch at the closest Zombie again!

Reckless Attack: 19

Damage: 15

„You almost got them all,“ enthusiastically comments Tez the abating battle. (No other action)

Eima feels a giddy feeling as Tymmy slashes through the zombie. She keeps her bonfire going and readies for the next zombie to come into view. (Assuming the zombie didn't make its undead fortitude save.)

Create Bonfire
Damage: 1 fire
DEX Save DC 13

Bonus-Action Steady Aim

Action: Ready attack on next zombie to come into view
To-Hit: max(5,20) = nat-20 Critical Hit, booyah! :D
Bow Damage: 4+1+3 = 8
Sneak Attack: 5+5+5+2 = 17
Total: 25 piercing!!!