[duelist17]

Now, Hear me out. This idea is actually based off a lot of gameplay mechanics(That would actually make void gate useful for once) and lore. I believe VA's should have a skill that makes void gates invisible (Like stealth trap makes traps invisible for rogues), or just make them invisible normally. Why? This might be long, but I actually have arguments about it instead of just demanding it so, Let me explain - they are using the poorly understood teleportation phenomenon that the mages guild uses to transport people so that they can teleport short distances quickly (This is from the wiki). As we know, Mages guild teleportation is safer, because it has a set point A and point B all the time, but there are no visible portals anywhere to be seen. If a portal like that existed, it would have been very easily seen, like a void gate of some sorts. But we are getting transported via an invisible connection from point A to point B. So, if Void Assassins are using this phenomenon as their basis, why would they be creating seeable portals? Also, one more Lore argument - Blink is a prime example of what copying the mage guilds teleportation technique would look like, and as I have said, with blink, you are also making an invisible point B and teleporting to it, While point A is yourself, basically wherever you are at. Furthermore, Vanishing Strike is also another great example on how there doesn't need to be any visible portals for teleportation to occur, so it doesn't make sense for void gates to actually be visible. The Fact that void veil is an invisible cloak, also establishes my point that VA's do have the ability to make something connected to the void invisible to the naked eye. So, considering this, Void Assassins void gates should in no way be visible.
Now, that was the lore part of the argument. let me go into the gameplay part. Remember the part I mentioned that was in the wiki. They use those portals to teleport short distances "quickly". The problem here is that there is nothing quick about it. Let's do a momentum based calculation and assume we don't have the passive equipped that would automatically fray them(Because that would make it 100% less worth it than any other mobility in the game, you are using one round to set it up and wasting 4 momentum if you teleport the next turn, and won't be able to teleport back to that spot ever again). The only way void gates have a better momentum usage is when you teleport to the same void gate a second time, because that would count as 2 mobility moves for 5 momentum. Which is technically better than others, since they would take 6. But...The point B is already set, so your opponent is most likely not there anymore(Not to mention he even more likely moved after the round the void gate was placed, so teleporting there would accomplish nothing in that situation too). Basically, how are they teleporting "quickly" if you are giving your opponent time to look at the void gate, be like "hmmm, i don't want to be here" and then they move away from it. Now, I tried to use this mechanic as an advantage of some sorts. Like - If you make your opponent move because of a void gate you will make them waste momentum. Well, if you thought like this, you were wrong, just like I was. Because literally every class combo in the game will have some sort of mobility that will not only move them out of the void gate, but also damage you in the process. Basically making that void gate investment useless, you just traded HP, FP, 3 Momentum and positioning for a void gate that might only be useful now for escaping that situation. Needless to say, worst trade ever. 
Void Assassins trademark is the void gate. And I see absolutely no reason for using it, why would I, I will just sub a class that actually has good mobility skills. Although Void Assassins trademark is also being able to teleport "quickly" and be mobile. You see the problem here?
So, the suggestion I had was to make void gates invisible to everyone involved(Yes, even the user). As I mentioned above, it makes sense lore wise. This will add a certain kind of "mind game" for the opponent, not knowing where the VA will appear from. and will make the skill more useful with a slight change like this. Also for the VA, they have to remember where they placed their void gates so they can teleport to them(While u can still make the gates visible only to the user, I am against that, it makes no sense to me, unless you add a trait or another skill that makes this possible). Just make the VA waste 1 momentum(or more) if they mess up and click an empty space instead of a void gate for now. Although, this will only be for now. Since void poisoning will most likely be a mechanic in the game (Like a 0-100 bar like physical stamina that starts with 0 and increases a little with every risky skill usage, when it reaches 100 you will develop stage 1, reach it again, stage 2, etc), I think it would be better to make the VA not only lose that 1 momentum, but also make them more exposed to the void because of their slipup, increasing their chances of poisoning. This will add a skill based ability to a rogue with an element for mind games with your opponent, which both should be a thing when you are playing a rogue class in my opinion.
Some interactions with this new change - They will become visible when frayed(Obviously), void refraction would work the same way, just need to aim at an invisible void gate. Although I don't understand this skill at all lore wise, those portals can't be stepped into from what I understand, if a person can't step into portal A and come out of Portal B, why can a projectile? That's a different topic though.
Hopefully I presented enough arguments about this change that I think would make sense not only lore wise, but would help make the skill more applicable to the class, since their identity should be connected with them using those void gates. But right now, using them isn't worth it at all, so You don't even feel like you are playing a class called "Void Assassin". Thank you for reading this huge wall of text, I just wanted to give reasons about the change instead of a blind suggestion.

[Snake]

It's just not seen visually due to, you know, game limitations. And making voidgates invisible would make them annoying.

They're already a bad way of transportation anyway due to how inefficient they are, momentum-wise, and I believe the concept of Voidgates should be touched one day or another. The fix would actually be fixing their use in combat, not giving them things the class doesn't need, imo.