Would it be balanced to houserule that 9th-level monks can use Unarmored Movement to stay on vertical surfaces or on liquids without falling?

Question

So right I've seen some discussion on here about the monk's Unarmored Movement feature and how it should be interpreted, and there are a lot of different ways. The main thing I've seen is that the monk either falls after the 6 seconds in the round or when they stop moving.

The way I originally thought it would work was that the monk could just stick to the wall similar to Naruto, in which characters fight on the sides of mountains and stuff because they hold themselves there with their Chakra (which is kind of the equivalent of ki in Dungeons and Dragons). So I assumed that because of the ki, they could hold themselves above water and on vertical walls similar to spider climb.

Would it be balanced to houserule that 9th-level monks can use Unarmored Movement to stay on vertical surfaces or on liquids without falling, even if they end their movement there?

Answer 1

Without some limitation or cost, this houserule ability could be easily exploited.

The idea you've proposed would allow the monk to remain on a vertical or liquid surface, even after completing their movement. Without any further restrictions, this has some unusual consequences. The monk could walk across a sea, or walk up a mile-high vertical cliff wall, or rest on such surfaces indefinitely. This may not fit the narrative concept that you had in mind.

From a mechanical standpoint, your houserule allows the monk to continuously walk on vertical surfaces, but without any of the normal costs. For that reason it is likely unbalanced. Normally, this benefit has a cost.

• The Spider Climb spell has a limited duration (up to 1 hour). It usually requires either a scroll, or a spellcaster to use a spell slot and concentration.

• Slippers of Spider Climbing, an uncommon magic item, have no per-use limitation, but there is an opportunity cost because they require attunement.

Here are some possible ideas for restrictions that could balance the houserule:

• After moving, the monk must make an ability check (such as Athletics or Acrobatics) to stay on the vertical or liquid surface.

• The monk can remain on these surfaces for a limited duration, such as several rounds or minutes.

• The monk can only activate this ability a limited number of times per rest.

• The monk can only use this ability when conscious and not paralyzed, grappled, etc.

It's your houserule, so the cost adjustments are for you to decide.