I honestly think this feature is pretty straightforward. Glide explicitly says you are moving horizontally, and it is explicitly optional (which means, unlike falling, it isn't forced movement). Moving voluntarily spends your movement. There doesn't seem to be a lot of wiggle room.
If you want to look at design intent, compare the other two options at this tier: Swim speed and Climb speed - two situational mobility features with very low power budget that don't actually increase your general speed. Fall damage negation/reduction and a niche but flavorful mobility trick seems to be right on par with that. A general glide/dash feature that greatly and consistently increases your speed is far, far better.
Movement is a specific action you take on your turn. If you fall outside of on your turn, how would the game handle the glide as movement? The only actions you can perform outside of your turn are reactions and held actions (and abilities that specifically trigger outside of your turn like the Vengeance Paladin movement), neither of which would cover suddenly falling because say, an enemy unexpectedly pushes you off a cliff on their turn. This tells me it is still considered falling, because there are situations the rules cannot handle treating it as movement.
Aethelwolf came to the same conclusion I did. Which may, or may not be right, but at least is balanced (compared to being able to glide 1000' per 6 seconds with a high enough starting point).
There aren't a lot of (any?) other optional movement that aren't limited in some way.
And even if the DM decides that it does use movement and can only be used on your turn, you can still fall 100 feet without taking damage. That's not nothing.
Aethelwolf came to the same conclusion I did. Which may, or may not be right, but at least is balanced (compared to being able to glide 1000' per 6 seconds with a high enough starting point).
There aren't a lot of (any?) other optional movement that aren't limited in some way.
And even if the DM decides that it does use movement and can only be used on your turn, you can still fall 100 feet without taking damage. That's not nothing.
Two people coming to the same conclusion doesn't mean you are correct.
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.
Using the word move in this ability is not the same as talking about the D&D specific vernacular that covers movement as a turn specific action. There is one trigger listed to be able to use this ability: falling while not incapacitated. If they wanted it to be used on only your turn they would have written such a clause into the ability like they do quite regularly with other abilities.
Maybe they forgot to add that clause. But pondering over the designer's intent is pointless to determining RAW. RAW, if you fall and are not incapacitated you can glide.
Whether you find this ability out of bounds in terms of power level is also irrelevant to determining RAW. WotC has printed ridiculous abilities before. I really don't think this ability is ridiculous at all, but again that doesn't matter when trying to determine RAW.
I know I'm late to this thread, but I'd just like to add that this glide feature is still forced movement, simply because you can't stop it. You are falling. Regardless of the fact that you are falling at an angle, you are still falling and you cannot stop the fall until you splat. So yes, you fall 500 ft. a turn and as a hybrid that means you can glide 1000 ft. a turn... but you take falling damage because you are falling... so whether you calculate it as falling 500 ft. (minus the 100 feet damage reduction) and take 40d6 splat damage or 1000 ft. and take 90d6 splat damage. Either way, the further you move, the more you are going to hurt.
The "you can subtract" and "you can move 2 feet horizontally" is simply choosing whether you fall straight down or at an angle. It is not choosing whether you move. You are moving... it is forced... it is forced movement and you have no choice in the matter.
Aethelwolf came to the same conclusion I did. Which may, or may not be right, but at least is balanced (compared to being able to glide 1000' per 6 seconds with a high enough starting point).
There aren't a lot of (any?) other optional movement that aren't limited in some way.
And even if the DM decides that it does use movement and can only be used on your turn, you can still fall 100 feet without taking damage. That's not nothing.
Two people coming to the same conclusion doesn't mean you are correct.
Using the word move in this ability is not the same as talking about the D&D specific vernacular that covers movement as a turn specific action. There is one trigger listed to be able to use this ability: falling while not incapacitated. If they wanted it to be used on only your turn they would have written such a clause into the ability like they do quite regularly with other abilities.
Maybe they forgot to add that clause. But pondering over the designer's intent is pointless to determining RAW. RAW, if you fall and are not incapacitated you can glide.
Whether you find this ability out of bounds in terms of power level is also irrelevant to determining RAW. WotC has printed ridiculous abilities before. I really don't think this ability is ridiculous at all, but again that doesn't matter when trying to determine RAW.
I know I'm late to this thread, but I'd just like to add that this glide feature is still forced movement, simply because you can't stop it. You are falling. Regardless of the fact that you are falling at an angle, you are still falling and you cannot stop the fall until you splat. So yes, you fall 500 ft. a turn and as a hybrid that means you can glide 1000 ft. a turn... but you take falling damage because you are falling... so whether you calculate it as falling 500 ft. (minus the 100 feet damage reduction) and take 40d6 splat damage or 1000 ft. and take 90d6 splat damage. Either way, the further you move, the more you are going to hurt.
The "you can subtract" and "you can move 2 feet horizontally" is simply choosing whether you fall straight down or at an angle. It is not choosing whether you move. You are moving... it is forced... it is forced movement and you have no choice in the matter.
ImeanIknowthatyouractionsleadinguptothefallmatterandthatyouareultimatelyresponsibleforthesituationsyoufindyourselfinbutonceyouarefallingandthisfeaturecomesintoeffectthereisnothingelsetobedoneaboutit.