Can you unhorse a rider using involuntary movement? [duplicate]

Imagine a rider on a horse. Imagine the rider is hit with involuntary movement. Will the rider be unhorsed?

At first, when contemplating this question I inferred that a rider must be grappling the mount. Involuntary movement beyond the rider’s reach would therefore force a dismount. It all seemed consistent. I chose to ignore that a grappled pair has a movement speed of zero.

Then I found the Mounted Combat rules:

If an effect moves your mount against its will while you're on it, you must succeed on a DC 10 Dexterity saving throw or fall off the mount, landing prone in a space within 5 feet of it. If you're knocked prone while mounted, you must make the same saving throw.

That this rule exists tells me you are not technically grappled to a mount as it describes an entirely different mechanic. The rule makes very clear what happens if your mount is affected by involuntary movement. What I can’t find is what happens when the rider is affected by involuntary movement. It's an unfortunate omission.

Take the simple 10-foot Repelling Blast Eldritch Invocation (or any similar 10-foot involuntary movement). That would seem to eject the rider from the mount, though I’m open to counter arguments. There is no option not to move 10 feet by making a mounted Dexterity save with Repelling Blast. There is no rule that would force the mount to move with the rider that I can find.

Now take the Telekinetic feat or combat action Shove. Upon success, this moves a target 5 feet. Short of a wall there is no option for the rider not to be involuntarily moved. If you shoved me 5 feet while riding a horse I would fall off the horse. A rodeo rider might not. If a rider were considered grappled to a mount, then it would not be sufficient to break the grapple, as the mount would remain within the rider’s reach, but I’ve already concluded the grapple rules do not apply. What to do?

Questions:

1. Would a 5-foot involuntary movement affecting a rider force a dismount? If not, what happens?
2. Is there any 5e mechanic infantry might use to unmount a rider?

My conclusion is that any involuntary movement affecting a rider of a normal one-size-larger mount forces a dismount. Grapple rules do not apply.

That out of the way, would you do anything different if a creature were lashed to a mount? I ask because in the same encounter that I used the Telekinetic feat to dismount a rider we also had an unconscious character lashed to a horse involuntarily knocked into a raging river. Good times.

• Does this answer your question? How does forced movement affect a rider? Dec 19, 2021 at 11:15
• Also @PurpleMonkey and others, the question mentioned 5e, so I’m not sure why we closed this for needs details. What details do you all think need to be included? Dec 19, 2021 at 12:04
• @ThomasMarkov I think this question needs to focus on one of the two aspects presented (and the first one would be a dupe, so it should probably focus on the second question). Dec 19, 2021 at 12:31
• @ThomasMarkov to be honest I only skimmed through the question and with all the mentions of 5’ I must have missed the 5e. But yes, as Akixkisu said, question 1 is definitely a duplicate but question 2 should be alright if the whole question is narrowed to focus on that. Dec 19, 2021 at 20:44
• 5e is correct. The question is what happens when a rider is involuntarily pushed off a mount. The linked question seems to be a duplicate, but none of the responses answer the question. One answer attempts a guess, but nothing one could consider official. The answer must be 1) You fall , 2) You don't fall, 3) The rider and the mount are a unit and you both move, 4) The rider and the mount are a unit so use the same rules as if you involuntarily moved the mount. That's all the answers I can think of. The second question is relevant and interesting, but not what I need to know at the moment. Dec 20, 2021 at 3:49

1 Answer

First, you are probably not grappling the mount. Grappled is a special condition in which something is reducing a creature's speed to 0, you are probably not doing that to your mount intentionally.

The mounted combat rules are really skinny. There are rules specified for what happens if your mount is involuntarily moved, and what happens if you are knocked prone on the mount.

In this case, where you are invountinarily moved and not knocked prone, there's no specified rule. So as the DM, you make the call.

Depending on the effect, the rider probably already had to make a saving throw of some other kind or the attacker had to roll to hit (in the case of Eldritch Blast). There's nothing specified in the rules that they aren't pulled off mounts by forced movement. You can decide based on the effect.

Players also have the creative opportunity to try to hedge against this problem in the future (such as tethering themselves to their mount, or building a special saddle, etc)