So this is my overall feedback for Vauban and I will just go over every ability however it will be long.
Tesla Nervos: The Tesla's to me are pretty good, however I really do not like how all the Tesla's can choose to stick on one target especially when using the Augment "Tesla Bank" which just makes it harder to spread the damage, I would change it so that each Tesla picks a target not already affected by one.
Tether Coil: I think this ability is actually pretty good, but if I was to change this I would just make it so you can only have 1 out but it holds 8 targets instead of having 4 that only hold 2 because it is kind of clunky to keep spamming it to get actual results out of it considering this game is very much a horde shooter.
Also the pull seems to be inconsistent, my hunch is that the enemy being dragged onto the floor is slowing the pull until there is no momentum left, so they're just stuck on the ground about 10-15 meters away from the Tether Coil, not sure how you would go about fixing that.
Flechette Orb: Honestly this ability is really good imo even with just 100% power strength, the damage is okay enough to where it can kill around level 60 corpus or infested when you have 4 of them out making it a pretty decent low level farm / clear tool, it can even work on some of the Grineer when you strip their armor first with Bastille, only thing I would really change is probably the damage type from puncture to something else, or maybe just increase the damage to 400 - 500 base instead of 300 to help it scale better.
Vector Pad: Personally this is just a nerfed Bounce, I would just make it have a 300 second duration with limited charges exactly like how Bounce was and maybe make allies who touch it gain some form of speed buff for a bit.
Overdriver: This ability is surprisingly the worst one in the entire Minelayer in my honest opinion because how how unbelievably clunky this ability is. The ability can only buff up to 4 entities with it and it is REALLY hard to control who you want to buff with it considering everybody is jumping around, it will target EVERYONE'S Sentinels, Kubrows, Kavats, and MOA's, it will even target Vaubans Tesla Nervos with which he can have 4. It feels really bad to use like this in its current state I would personally just make it work in a similar manner to how "Smite Infusion" / "Venom Dose" / "Freeze Force / "Shock Trooper" Etc work, in which you just throw the mine and it blows up in an AoE and buffs everybody in that blast radius with it instead of it being capped to 4 people and being prematurely taken off if you buff something else.
Photon Strike: This ability is also a really bad one, the damage is not enough for how long it takes and how much setup is required which in turn takes a lot of energy and you definitely are going to need a low efficiency blind rage build just to make this one ability relevant and even then....... I have a gun, a secondary weapon, a melee weapon, and even a companion that is more relevant than this ability in all honesty. I am really disappointed that Vauban never got some form of shield in his 3rd skill slot considering he is an Engineer, even more so with how he has really low survivability, and if I was to replace this ability with anything it would be a shield of some kind. Also the augment just encourages a play style that just is not fun at all, group enemies up wait 2 seconds and then it hits 5 enemies then cast again wait 2 seconds then keep gathering enemies up with more blind rage effected vortexes or coils, and it is really tedious when i can just kill them all with my gun and the assistance of just vortex or those tether coils and then be done with it and is also very energy inefficient especially considering your gonna have to run blind rage to make this relevant.
Bastille: This ability is pretty much the best part of the rework in my opinion but I would definitely make it cost 75 energy instead of 100 like MANY people suggested already, also I would like to see the armor buff match the duration of the actual Bastille so your not required to use it as much to keep that going for any semblance of survivability.
Tesla Nervos: Make it prioritize unaffected targets instead of just stacking all 4 on 1.
Tether coil: should be 1 mine with 8 targets instead of 4 with 2 each, also fix inconsistency bug with it.
Flechette orb: needs either slightly more damage or a different damage type.
Vector pad: should just be like the old bounce (300 sec duration, charges) and maybe a speed buff too.
Overdriver: (might wanna skip to that section of my "book" since that is hard to summarize).
Photon strike: redundant, useless, would rather have a shield instead definitely would replace.
Bastille: make it 75 energy instead of 100.