Yep it would have, sorry I thought there would have been different rules for climbing speed opportunity attacks since it’s not technically going past a creature rather it’s just going above, but if you want to make an opportunity attack you can do so, though since the monster is already retreating and if you damage it that’ll cause your weapon to take another -1 penalty, I don’t see much reason why you would want to. Still if you want to attack go ahead. 

As the monster crawls away from him, Bilyur launches his fist out, hoping to prevent the creature from escaping. 

Unarmed strike: 19 to hit, 5 damage. 

Quote from Shiverquill >>

Also, this is completely unrelated, but I’m playing Storm King’s Thunder with my IRL group soon and I’m complete stuck for character ideas, we’ve got a Wizard, Barbarian, Artificer and Fighter so far so does anyone have any ideas?]

[[
Firbolg druid? Get that giantkin nature-lover added.
Goliath sorcerer. Giantkin again. Get the carrying capacity despite low strength. And the stone's endurance will come in handy for making your fragile hitpoints go further.
]]

You plant a fist into the creature, pummelling it into the wall as it collapses into a soggy grey goop mess, dead. What would you all like to do now? 

Quote from VitusW >>

Quote from Shiverquill >>

[[
Firbolg druid? Get that giantkin nature-lover added.
Goliath sorcerer. Giantkin again. Get the carrying capacity despite low strength. And the stone's endurance will come in handy for making your fragile hitpoints go further.
]]

 [Those are some pretty good ideas, I reckon a Goliath Storm Sorcerer that’s reflavoured to be snowstorm or blizzard based could be really cool, and a Firbolg Druid could be very versatile though our barbarian’s a Firbolg so there might be a bit of overlap, but I could talk to them and maybe we could link our backstories and have them come from the same tribe to explain it? Either way those are some great ideas thanks] 

Sly looks back and forth at the martial spectatle unfolding in front of her without having to lift a finger.

"Well", she says, moving a stray lock of pale purple hair out of her face, looking down at the shriveling mess.
"I suppose pummeling monsters into submission in short order is a good character trait to have."

She looks at Aidrey. "You must have followed me in. Sly. Pleasure."

Hearing the words from Eggo, she nods. "Quite. If one chooses to believe the tabloids, digging deeply is how one finds the greatest treasure."

If the party moves on, Sly will prefer to take up the rear position.

“Thanks for the help. I thought that key was going to alert the now-dead rabbit.” Aridrey says to the gnome.

Aridrey then turns to Eggo. “The key alerted a slime, which he killed.”

”Speaking of which, is that your only weapon?” The halfling gestures to the gnomes shortsword.

“Aridrey.” The halfling replies to Sly. “Nice to meet you as well.”

((Slightly confused the characters, but will roll with it))

Sly also nods to Bilyur, introducing herself and saying "swift fists and feet you have there gnome, well met".

The gnome looks at his corroded blade. "No. I also cary darts, though this is my only melee option. However, I usually fight with my fists, so losing it is not much of a problem. I am Bilyur, and I seek not treasure but honor. May I ask who you are, friend?'l"

Quote from Preyfire >>

((Slightly confused the characters, but will roll with it))

[[ Current Characters are:

Eggo Lass: Drow Warlock, played by VitusW
Tharkun: Tiefling Wizard, played by Teufelshunden
Bilyur: Gnome Monk, played by RippedRhinoVikings
Galochka: Thri-Kreen Barbarian played by Agni_Gnus
Hugh: Halfling Rogue, played by AkodoDani
Aridrey: Halfling Paladin, played by Pyrothornthebrave
Sly: Tiefling Wizard, played by you of course

There’s also another player Bjorn_Stahle, who should be playing a Human Ranger. They’ve PMed me a few times but haven’t actually posted anything here from what I’ve seen, though they did say they’ve read through the thread and have a method for introducing their character, which I might have to do for them

I know it’s a lot of characters but I feel that each is distinct enough that you’ll be able to tell them apart eventually, and if you associate them with their player (and text colour if they use it) you might pick it up a bit quicker :)]

[[Thank you for the summary, that's very helpful. I'm going to wait for the others to add their opinions on in which direction to go. Sly is clearly eager to go on.]]

[Awesome, really there is no where else to go on this dungeon other than moving on to the second, but I’ll let the group make that decision in case some one still wants to look at something, though there really isn’t anything left to do in this dungeon]

“I wouldn’t mind going into the next dungeon. Though, I don’t want to leave Aria unconscious here.” Aridrey says. ”Or unsupervised.”

“Anyone else have anything they want to do here?”

Sly frowns. "Oh yeah, about Aria. That triton guarding the portal told me that it is one-way. It seems we have no choice of taking her with us. She has no way to leave, and being alone here is a surely a death sentence."

[Btw whether or not you take Aria with you, thought I’d just state that she uses the Bard stat block from MoM, though she is currently suffering from 3 levels of Exhaustion and will be unconscious for at least another hour before she awakes]

[I’m not familiar with all the acronyms. What’s MoM?]

[Monsters of the Multiverse, sorry in future I’ll type out the whole thing :)]

“There’s a triton guarding the portal? Do they want us to fight them, or solve a riddle, or something else?” Aridrey asks Sly.

[They mean Asriech, the triton guarding the original entrance portal under the arch at Aerod Hill you encountered at the beginning. The portal to the second dungeon is fully open and ready to be walked through as you killed the rabbit guarding it]