Can a mule benefit from a Phantom Steed?

Question

The phantom steed spell creates a "Large quasi-real, horselike creature" that can be ridden by "you or a creature you choose". "You decide the creature’s appearance" and it "uses the statistics for a riding horse."

The rules for mounted combat state that "A willing creature that is at least one size larger than you and that has an appropriate anatomy can serve as a mount"

Can a mule ride on a phantom steed?

The conditions appear to be that (1) the Steed is willing (which I think we can assume from the nature of the spell), that (2) it is a size larger than the mule (Mules are Size Medium, Riding Horses are Size Large), and that it (3) has "appropriate anatomy".

Now, obviously a real riding horse does not have an appropriate anatomy to be ridden by a mule.

But the phantom steed is not a riding horse. It is a "horselike creature", whose appearance is decided by the spell's caster.

So, RAW, does anything prevent the caster from stating that the steed created has its appearance including appropriate anatomy to be ridden by a mule, any other size medium or smaller quadruped, or other non-traditional riders?

Answer 1

At the GM's discretion.

The size is appropriate. The willingness is also clear since the spell specifically states that the caster or another designated creature can ride the phantom steed.

The condition of appropriate anatomy is rather vague which may be because it is rather clear what animals / monsters a human(oid) can ride on. It is unclear, however, what the appropriate anatomy is when the mounted combatant is a mule. "Horse-like" and using the Riding Horse stat block indicate that the appearance cannot be completely freely decided.

In the end, however, it is up to the GM to decide how far you can deviate from the standard horse and, more importantly, if "appropriate anatomy to be ridden by a mule" is a sufficient description of the appearance. The GM is clearly within their right to have you describe how the anatomy is appropriate.

Answer 2

There is a rule that potentially limits this interpretation

Your interpretation is likely an unusual one but it obeys a strict reading of the rules. Page 6 of the PHB includes what is commonly referred to as "Rule Zero" which describes the flow of play:

• The DM describes the environment.

• The players describe what they want to do.

• The DM narrates the results of the adventurers' actions.

Here, the DM is given the power and responsibility to adjudicate whether a mule riding a Phantom Steed is possible. I think the player attempting to stack equine mounts in this way would have to "sell" it and describe how the Phantom Steed is shaped to permit this arrangement, but if the DM agrees that it is possible, there is no other conflict preventing it.

In fact, if the DM says it's possible, this decision would override any other rules conflict.

Answer 3

Possible with DM blessing

Part of the wording is, "you or a creature you choose can ride the steed". While you might be able to envision a "horselike" creature that could carry the mule, the mule itself is incapable of the verb definition of "riding".

"sit on and control the movement of..."

The mule would just be cargo which means it is likely just draped over the back. Which brings up the other definition.

"a journey made on horseback, on a bicycle or motorcycle, or in a vehicle."

Which would aptly describe what you're wanting; the mule is "along for the ride".

It just depends on if you and your DM see ride as a noun or a verb.

But beyond verbal gymnastics, there is the question of how to get the mule on the steed and keep it there. My experience with mules would suggest they would not like to be in the saddle and carried and would keep kicking and flailing to get off.

The Phantom Steed does come with a saddle, but it may not prove to be enough when the creature doesn't want to be there in the first place.

So it's really a "Talk to your DM" case, and if you can make a good story, you might have a chance.