Does the Jump spell stack with the monk's Step of the Wind ki ability?

Question

Inspired by this question, I wonder about the Monk feature (PHB p. 78):

Step of the Wind

... Your jump distance is doubled for the turn

And the jump spell (PHB p.254):

Jump

... the creature's jump distance is tripled ...

With regards to this rule (PHB p. 205):

Combining Magical Effects

The effects of different spells add together while the durations of those spells overlap. The effects of the same spell cast multiple times don't combine, however. Instead, the most potent effect - such as the highest bonus - from those castings applies while their durations overlap.

So, what happens if you do them both?

1. x3 because they are the same and "don't combine" (not my favourite)
2. x4 because they "add together" - 1 + 1 (double for SotW) + 2 (triple for Jump)
3. x5 because they "add together" - x2 (SotW) + x3 (Jump) = x5
4. x6 because they "add together" - (base value x2 for SotW) x3 for Jump

At my table it would be 2., or maybe 3. but then again I could go with 4.

I would like to see what support there is for other interpretations in the rules, published modules or other WotC info.

Answer 1

The rules you've quoted on combining magical effects are unambiguous - these two effects stack, since they're not from the same source.

As for how they stack, the answer is your fourth choice. While in previous editions the rule was that multipliers stacked additively, not multiplicatively, 5e has no such rule. Likewise, 5e has no concept of "base value". When you use Step of the Wind, your jump distance is doubled. Then when you use Jump, your jump distance is tripled.

It should be noted that High Jump, like Long Jump, states that each foot you jump costs a foot of movement, so the distance you can jump is still constrained by your move speed. Obviously there are numerous methods of getting a very high move speed, but it is still an important constraint on your ability to leap skyscrapers in a single bound.

Also worth noting is that, as the highest rated answer on your linked question says, you still take falling damage when you jump, so another constraint on your ability to jump into the stratosphere is the damage you will take when you land.

And finally, to dismiss any concerns about balance, I have to point out that this requires a 1st-level spell and a 2nd level Monk feature to pull off, and Fly is a 3rd-level spell. And that's not even mentioning the fact that you can reasonably expect to be fighting flying enemies right from the start at level 1. This "super jump" is a cool trick, but ultimately not that useful or powerful.