The arena: Monster killers.

(Bonus action, move Hunter's Mark to the second Hadrosaurus, concentration)

Attacks Hadrosaurus, Longbow, Hunter's Mark, Colossus Slayer: 19 Damage: 16

That takes Dino no.2 down! The hallway is now almost all blocked. 

Dolrik, you’re up!

Seeing Count’s firebolt disperse harmlessly on the enemy spellcaster, Dolrik will ready Toll the Dead against the elusive foe, to trigger the moment they appear.

DC 14 Wis Save or 8 necrotic

or

10 necrotic damage, should they be damaged before being hit by this spell.

Nadir and Count, you’re up!

Nadir gets into position to peek through some hole at where the enemy spellcaster last appeared and gets ready to Create Bonfire at their position as soon as they reappear.

Dex DC 14 or 6 fire damage. (This roll was a 2 in case it changes)

"Set a fire up behind where he keeps popping out from." Count will ready a Gust to push the spell caster back 5 feet, hopefully into a bonfire.

Str save DC 14

(Crap, similar idea at least!)

Save vs toll 8
save vs bonfire 12

save vs gust 10

She shoots a ray of frost at Nadir and ducks back behind again Attack: 20 Damage: 6

Also, a giant rat squeaks out of the side door! It runs up to the Dino’s but can’t get over em this time. 

You, you’re up!

(Bonus action, move Hunter's Mark to the "rat" Guthash, concentration)

Attacks Guthash, Longbow, Hunter's Mark: 21 Damage: 16

Whoop te do, down she goes with a thundering thunk, Dolrik is up!

(I can tell my brain is starting to go crazy be reading what I just have wrote)

Ready Toll the Dead on the spellcaster when she pops out again.

DC 14 Wis Save or 5 necrotic damage.

Nadir climbs over the dead dinos and readies a spear throw attack at the caster when she shows herself again.

Attack: 25 Damage: 10

Count, your turn. 

Count will start moving down the hall towards the caster. (Full movement over dinos and down hall if movement left and action will be dodge)

Sir Spitz will stay behind the dino shield

The caster steps out, straight into Nadir’s thrown spear. She attempts to shield, but it bursts through the magic and sinks itself straight through her head…

(Odds you fight another wave, evens you get a long rest.) 6

From this wave you get 67 xp, a shortsword, a hand crossbow and 4 poisoned bolts. You also get 10 gold. 

Here is your current total pile, what would you like to do with it all?

XP:1732

GP:804

SP:332

CP:25

Rapier x2

Spear x11

Javelin x19

Leather armor x5

Hide armor x2

Club x6

Morningstar

Breastplate

Shield x3

Hand crossbow x1

Shortsword x2

Scimitar x2

Shortbow x3

Dagger x4

Light crossbow &20 bolts

Trident

Hand crossbow and 4 poisoned bolts