Could a Simic Hybrid Echo Knight stay aloft as long as desired?

Question

So I was reading over the Simic Hybrid's possible adaptations and noticed Manta Glide:

You have ray-like fins that you can use as wings to slow your fall or allow you to glide. When you fall and aren't incapacitated, you can subtract up to 100 feet from the fall when calculating falling damage, and you can move up to 2 feet horizontally for every 1 foot you descend.

So I used to cast Dimension Door 500 ft. above myself and then travel 1000 ft. in a turn. But my DM is a "RAW strict bitch" (her words not mine) and accepted this answer.

So trying to break the game the other way I now Dimension door straight up and then glide down slowly over the next 33 turns (since DM won't let em take more than 30 ft. of movement, I only have to descend 15 ft.).

Comparing this to 4th level fly it has half the speed, half the duration, half the targets, and half the up/down control, but it doesn't cost my concentration.

My idea however is that if I take 3 levels of Echo Knight (DM now allows the critical role classes due to Vox Machina) I'd basically be getting unlimited Misty Step spells so long as my Echo stays alive.

You can use a bonus action to magically manifest an echo of yourself in an unoccupied space you can see within 15 feet of you. This echo is a magical, translucent, gray image of you that lasts until it is destroyed, until you dismiss it as a bonus action, until you manifest another echo, or until you’re incapacitated... If your echo is ever more than 30 feet from you at the end of your turn, it is destroyed.

As a bonus action, you can teleport, magically swapping places with your echo at a cost of 15 feet of your movement, regardless of the distance between the two of you.

Since my Echo can go upward 30 ft. a turn while I can limit my decent to 15 ft. per turn while gliding, does this mean I can stay aloft forever by turning in circles so my echo can catch up after we switch places?

Edit: My DM has had a change of heart seeing my new way of breaking the game (and having had more than one session to think about it, in her defense). She now interprets the fins to be more like wing suiter style fins. So I gain falling/gliding speed more appropriate for a wing suiter which half she has ruled at half that given in XGtE. So I "descend 250 ft. first turn, and each subsequent turn". Thank you so much to all who read my post and helped with an answer.

Answer 1

Yes, but your DM is using some unusual house rules.

If you're accurately describing what your DM has ruled, then yes, this ought to work. That said, those aren't the rules in the book.

The Player's Handbook doesn't specify how long it takes to fall; it merely says "at the end of a fall" you take damage based on how far you fell. Contrary to popular belief, this does not say that the entire fall happens instantaneously regardless of distance. The rules are merely silent on the matter.

Xanathar's Guide to Everything provides a more specific optional rule:

When you fall from a great height, you instantly descend up to 500 feet. If you're still falling on your next turn, you descend up to 500 feet at the end of that turn.

And then you keep doing that until you hit the ground or figure out a way to stop falling.

By the rules as written, the manta glide ability does not change your fall rate, it just lets you move laterally in addition to the fall and reduces the impact damage for relatively short falls. So going by the Xanathar rules, you would immediately descend up to 500 feet, moving up to 1000 feet laterally at the same time, then at the end of each of your turns you'd do the same thing again. When you hit the ground, you'd take the damage for the full distance of your fall, less 100 feet.

Going by that set of rules, your plan makes no sense -- you and the echo would both reach the ground without even interacting with turn order for any fall less than 500 feet, and for falls longer than that, at best you could add one extra turn to the glide. (For example, if you were 490 feet up, adding 15 feet to that would put you just over the limit and stave off impact until the end of your next turn.)

The trick you've identified only works within the context of a slightly nonsensical ruling. (I call it nonsensical because, if your glide ability means you fall only 15 feet per turn, then you really shouldn't be taking any damage no matter how far you fall, as you are apparently going to hit the ground at a jogging pace!)