Only thing I would change would be the skelly line. As stated in the other thread, specialist lines should be specialized for each class. It would be best if other sets could benefit from any class. Perhaps when hitting a deathmarked enemy they suffer a MSI -1. That would mean either playing as a recon, or synergizing with a friendly recon, but the bonus would work no matter what your class.

And do these bonuses stack on top of the 5* versions in your other thread, or are they replaced by the other thread's powers? If it's a replacement it might make 4* sets more viable for the bonuses, which would be a welcome change and a nice way to introduce people to lockdown.

Just going to throw out a few loopholes that might need to be fixed anyways:
What if you wear one piece ash tail and one piece skolver? Would you get 33% from either's effect, or the fact that they are from the same "set" means you net the entire "wolver set" bonus, but not the full "Skolver" bonus? What about ash tail and dusker? Should users get the full benefit if it's the same line but just different star levels, unless the new star level introduces a different power?

Would damage bonuses work in smaller increments at 33% power? As such, instead of a ~7% damage boost, players would have a ~2.31% damage boost? Would this show on the tooltip, or just be invisible?

Also something else I should mention is that quicksilver's line should not have any sort of hazewalk ability lower than 5*, as the status walking abilities could only be triggered via trinkets or UVs. You need about +7 (may be 6.5) status resistance to hazewalk through minor statuses, and you do not have a natural 8 until 5*. An alternative would be shock spasms heal the quicksilver line by about 130 health, or ~3 pips of health. The fact that the line resists shock will make sure that the spasms happen less, and thus don't heal as much as someone with shock vulnerability might. You might even throw in a chance to shock yourself when using charge attacks.

And the skelly line still puts me off. I know you're trying to play on the idea of the skelly line bringing fear into its enemies, but forcing that role onto recons, while making sense, limits the usage of the armor. Like I suggested before, perhaps the MSD could be inflicted upon hitting a deathmarked enemy, or even maybe have it so you stun deathmarked enemies when attacking them. This allows for a guardian wearing full skelly to be viable, and a striker wearing full skelly to be reasonable when paired up with a friendly recon.

Still didn't answer the wolver to dusker, or dusker to ash tail question. I understand 4* to 5*, but I'd think a 2* to 3*, or 3* to 4*, or even 2* to 4* could make the game viable if the boosts worked with mixed star levels.

As for encouraging more classes in lockdown... The demo works the same for all classes, the wolver works the same for all classes, yet skelly works only for one class. Perhaps making skelly add a MSD to any enemy that is hit would make it viable. We might see players in full skelly gear as strikers if that is the case.

Players shouldn't be forced into a class if they want to reap the rewards of its bonus unless it is specifically specialized in that way. For example, a chaos user works for all classes. A skolver works as a recon and guardian as well as a striker. Grey Owlite will see okay usage for all classes.
What I'm saying is Skelly has no bonus usage to 2/3rds of the playable classes. It is a defensive armor, and it would see no usage on the class that is in defense.
In short, Skelly should do its bonus for all classes. Perhaps after shielding for so long it will apply the debuff. Perhaps a full 3 seconds of shielding would give you 5 seconds of attacks that apply MSD to enemies. A striker can benefit from it, but must exhaust their striker boost entirely in one go to get the bonus. Recons could deathmark AND get that bonus. Guardians could sit on points for a while then have the bonus right away.

That sounds like a great way to make skelly work! Perhaps it could create a big angry bomb that detonates about half a second after death? If not the bomb itself, at least have similar visuals, or perhaps a spooky scary skeleton instead of the bomb face.
You know, you could have something similar for all the 5* defensive sets. Dread skelly gets an explosion on death, perhaps royal jelly could spawn giant lichen colony spikes on death (the ground ones. Not as dangerous as dread skelly), and grey owlite could spawn the old radiant sun shard bits in every direction. This is something for your other thread technically, but it's a fun thing to think about.

Granted, I think only the skelly set really needs it, but it would be a welcome change.

And thanks for clearing up the mixed level sets. It would make players who only have one 4* item and want to try out tier 3 lockdown less at a disadvantage if wearing a set.

Jelly and Skelly definitely need something. Grey Owlite is just overshadowed by chaos as an elemental resistance. The statuses it resists are common (at least shock is. Fire is sort of rare), but it could perhaps have the weakest of the "death effects". Like, leave a 2* haze bomb at their feet that inflicts fire and shock, but lasts for 2 seconds tops. Not the greatest thing to rely on, but still a defense line comeback

Perhaps for skelly it drops 10 "haunted haze" ghosts to attack whatever enemy is within a certain radius? If there are more than one enemy, then the damage is spread out. This means running onto a point against all other players on the other team will deal pitiful damage to all of them, however if you died to one person alone, then they would take a reasonable sum of damage. Jelly could have less of a range (think of it having blind spots) but have the same amount of damage be shot out every time they died? Skelly could dish out, say, 400 damage total. That means each ghost does 40 damage, or one pip. You can't resist that damage type either. For jelly, it could deal piercing and each spike (8 total) could deal 160 damage (4 pips) at 100 resistance.

Quicksilver idea could work. The zip around could be emulated by having a massive MSI while shocked (backfire barrier speed!), but max ASD when shocked (cannot be overwritten with ASI uvs and such). Otherwise, the player acts normally while shocked, spasming and taking damage.

With quicksilver, perhaps have the player be resistant to elemental damage while spasming instead of all damage. Makes shocking a quicksilver with alch-switching, brandish charges, or wailing with hammer combos less effective while still allowing other damage sources to continue. A cutter would be great if the contact damage didn't hit you the moment they stop spasming. Contact damage would be low (at most 1 pip), but perhaps have a low chance to spread shock. If you get lucky, walking into an enemy will get you both into an endless loop of shock until they fall.

And that second idea could work too.
Owlite becomes the elemental resistance. Polaris reigning on you? No problem. Hammers flying everywhere? No problem. Brandish hits? No problem.
Skelly being the shadow resistance would change a lot I would think. Players might mix and match skelly with black kat gear and have great acheron and gran faust resistance. Granted they could get more if they threw the damage bonus from the black kat set out the window for the full skelly set, but I doubt many players would be willing to do that.
Jelly being the piercing resistance could see some use as well. As long as the piercing resistance makes a big enough of a difference. It should be the difference from 5-6 flourish hits to 7-8 flourish hits. Heck, if you're wearing the full set you might be able to take 10 hits from a flourish as a +12 health striker, and even more as a guardian. Max damage strikers might need to switch tactics if a jelly shows its face... Thing...

Essentially, making the defensive armors actually provide great defense is a big plus from me. Besides, in order to take them down all you need to do is stop using your flourish/hammer/acheron and carry a varied loadout. Nothing hard or impossible.