On Friday, May 13, 2022 at 2:35:52 PM UTC-7, Janis wrote:
> I ride a steed stepped onto a teleport trap that lead me into a
> niche. Searching revealed the door, but it's locked. I cannot
> unmount since there's no free square. [...]
You could kick and possibly be thrown off the steed. You
will end up still in the niche and the steed--former steed at
that point--will be displaced beyond the door.
The steed loses tameness when kicked, so even if you don't
get thrown off the saddle, with repeated kicking you will
eventually make it non-tame and be forcibly dismounted
for that.
Various other things can cause uncontrolled dismount and
produce a similar outcome. Polymorph of either the hero
or the steed are the only ones which come immediately to
mind but there are others.
Prayer won't help because the presence of the door means
that you aren't completely closed in by solid rock. I'm not
sure offhand whether it would have saved you if you had
tried it before finding the secret door which turned the
apparent wall into a door.
Successful prayer will rescue you when stuck in a niche
that has no door at all. Those are created with a scroll of
teleportation on the floor but if you're unskilled (so not a
knight since knights start out with basic skill) at riding you
wouldn't be able to pick it up.