Alternative Underdark Mounts

Question

I am currently working as the DM for Out of the Abyss and have a Paladin in my party. This means at level 5, I need to come up with a Mount for her.

Due to the Underdark being the Underdark, traditional surface world mounts aren't terribly useful. A Horse is going to have a hard time navigating the tunnels and cliffs and ledges and everything else that makes up the terrain. I don't want to give one of my players a basically useless class feature.

According to everything I have run across for 5E, there are only two types of creature used in the Underdark as Mounts... Giant Lizards and Steeders.

I would like to give her more options than that.

So, are there any other creatures traditionally used as viable mounts in the Underdark? I will gladly accept results from other editions of D&D...I don't mind re-statting things. The player is controlling a medium-sized character.

As my choice of tags and wording did not make this clear, allow me to clarify what I am looking for.

I am looking for a Mount for a Paladin using Find Steed at Fifth Level. It must meet the following requirements:

• Large Size
• CR no greater than 1 (CR of a Steeder)
• Is used in lore by Underdark races as a mount.
• Must meet the 'physical anatomy' requirements necessary to be ridden
• Must not have a Flying Speed
• Must come from official D&D material, or WotC sanctioned fiction

I am looking for another mount that is in the same 'class' of creatures as the ones that are already listed as options for the Find Steed Spell (warhorse, pony, camel, elk, or mastiff), but is canonically used as a mount in the Underdark, by one of the races that lives there. I am looking for an answer from official Dungeons and Dragons material, not homebrew, and would greatly appreciate a reference to the rulebook or D&D publication that contains this information. I will also accept WotC sanctioned fiction that features adventures in the Underdark and having a creature as a mount.

If no in-lore, canonical alternative exists, then 'there is nothing else' is a valid answer (assuming it is properly backed).

To be clear: I am looking exclusively for mounts used by the races of the Underdark, not mounts from the surface that could be useful on rough terrain or in caverns. I am capable of doing the research for other suitable non-Underdark mounts on my own and am looking to supplement this with lore-friendly Underdark options.

Answer 1

I did a search on D&D Beyond for Large Underdark creatures of CR 1 or below. From that here are the suitable mounts:

• Giant Lizard/Giant Lizard (Variant)/Giant Riding Lizard: This CR1/4 lizard has appeared a couple of places and seems a pretty solid choice.
• Giant Spider (AKA Steeder): You already pointed this out. CR1 and provided your table doesn't have an arachnophobe it's a good choice.
• Giant Strider: Introduced with Volo's Guide to monsters this CR1 creature is IMO the best choice. The book even says "striders voluntarily serve as mounts".
• Giant Toad: CR1 and if you don't mind hopping everywhere the extra jump distance can get you places other mounts can't.
• Half-Ogre: In theory you could but this is more of an NPC than a mount.
• Reduced Threat Carrion Crawler: A standard Carrion Crawler is CR2 but the reduced threat template makes this a suitable mount. Plus is has a climb speed.

Why the Giant Strider is the best option

Lets look at your requirements:

• Large Size - Check
• CR no greater than 1 (CR of a Steeder) - CR1 exactly
• Is used in lore by Underdark races as a mount - More so than any other option. This creature literally only exists in the lore as a mount for Firenewt warriors.
• Must meet the 'physical anatomy' requirements necessary to be ridden - Check
• Must not have a Flying Speed - Check
• Must come from official D&D material, or WotC sanctioned fiction - Published in Volo's Guide to Monsters.

I cannot see a better and more suitable option that the Giant Strider for an underdark mount.

Answer 2

A Giant Goat fits your needs; roughly the same power level as warhorse

A Horse is going to have a hard time navigating the tunnels and cliffs and ledges and everything else that makes up the terrain.

Using the same CR as warhorse (1/2) and the same HP (19) you can offer a Giant goat, and should be able to handle the tricky footing. It is large sized and thus can carry a medium sized creature. (MM p. 326/SRD 5.1/Basic Rules p. 132) A few salient points.

Giant Goat Armor Class 11 (natural armor) Hit Points 19 (3d10 + 3)
Speed 40 ft. {snip}
Sure‐Footed. The goat has advantage on Strength and Dexterity saving throws made against effects that would knock it prone.

It also has a charge attack, see the link for details.

Find Steed spell description extract

... the steed takes on a form that you choose: a warhorse, a pony, a camel, an elk, or a mastiff. (Your GM might allow other animals to be summoned as steeds.) The steed has the statistics of the chosen form, though it is a celestial, fey, or fiend (your choice) instead of its normal type. Additionally, if your steed has an Intelligence of 5 or less, its Intelligence becomes 6, and it gains the ability to understand one language of your choice that you speak.

Because the summoned steed is a spirit in the form of a giant goat, I see no obstacle to using one.

Now that the question has changed to only include lore-based Underdark mounts, this answer only fits if someone in the Underdark ever had a goat. As I have not read all Underdark stories ever, I can't say either way.

Answer 3

I don't speak for the canonicity of these alternatives, as I've not read the source material, but I draw the references from this website. I summarize here in the event of link rot. I'm only including the ones from the list that could conceivably be big enough to carry a person.

• Dire Bat
• Night Hunter [Monster Compendium: Monsters of Faerûn], actually not sure if this could carry a person. It has 7 foot wingspan, weighs 250 pounds. Given that the Dire Bat could be said to carry a person and weighs only 200 pounds (albeit with a 15' wingspan) it might fit the bill. Worth investigating.
• Riding Lizard you already mentioned but why not include it anyway for completeness.
• Monstrous Spider comes in several sizes, surely one big enough to ride. Probably falls under the "steeder" category you mentioned. Notably, there are several varieties of spider in the underdark, including the...
• Phase Spider
• Deep Rothe a fungus and moss eating musk-ox. Oxen can be ridden. You're looking for the "Deep" Rothe, not an ordinary, surface dwelling Rothe.

Answer 4

If you want material for an underdark campaign, the drowtales comic is set there and may provide inspiration. For your specific question, various drow clans in the comic use:

• Dire wolves, which have non-sight-based bonuses to perception. (Basic Rules p. 123)
• Pony-like dawmere. I don't think this is a DnD creature though.
• Giant spiders, as Doctor Kill mentions.

Sorry I can't provide pages for dawmere.

The golems and dragon like creatures in the comic don't fit into your CR restrictions.

Answer 5

Carrion Crawler, Monster Manual page 37.

It's a large creature (a monstrosity, not a beast, which makes a difference for some spells and features) with spider climb. I think its a GM call whether it has the strength and rigidity to carry a medium character. It should at least be able to carry small characters.

In our Out of the Abyss game, we recently came across a carrion crawler with a saddle on it. We are trying to tame it, as we think it would go well with the giant spider we already have.

Next, we need find a lizard, to gain the Monstrous Mount Trifecta achievement. :-)