Caustic Ultimate Buff

@Oknijam Caustic could use a buff, maybe.
But 35 damage? Are you out of your mind? That would take 3 ticks to kill you! Caustic's ult doesn't have much advance warning, unlike (cough cough) Gibraltar, Bangalore, and Crypto. Their ults all give time to escape or establish cover/shoot the drone. It's not like you can escape easily, either, as his ult blinds you and slows you.
Making it blanket an area as big as gibraltar or Crypto's ults would make it too op as well, as that is a huge area. If you get caught in the center, there is little chance on surviving, as the slow/blind+the enemy team will basically eliminate your chances of survival.
Sure, Crypto can emp you with 50 damage, but that's only 50 damage once. Caustic's gas stays a lot longer, can kill easier, blinds, slows, and highlights you for the Caustic player.

Caustic's gas traps don't stack because then a Caustic could toss down a bunch of traps in one area and deal way too much damage. Putting down 2 in one area would do 8 damage per tick, and then continue to increase to 20 per tick. Which is really strong. Putting down more in one area would be even worse, as then you can do 12 damage per tick-30 dpt, 16 dpt-40 dpt, 20dpt-50 dpt, and finally 24 dpt-60 dpt. That would be way too strong.
(Sidenote:Caustic's gas does kind of stack. Not quite in the way you want it, but if there are two traps in the same area, the second one will deal 1 dpt on top of the increasing damage from the other.)

Wattson's fences also don't have area denial. She is good for perimeter security or blocking off passageways, but not for straight up area denial. Because of this, her traps don't affect teammates, plus it would be really annoying to get slowed every time you want to walk through a fence that is blocking your door. Caustic's traps, on the other hand, don't activate until an enemy passes by or it is shot. It doesn't affect teammates until this point. Now since it is a good area denial, the advantage it gives your team if an enemy is caught in it is pretty big. They're slowed, partially blinded, and continuously taking damage.

@Oknijam Well, you said make it more “on par” with the size of other ults.
You don’t get killed by 3 ticks of Gibraltar’s and Bangalore’s ult either. They don’t have continuous damage, plus you’d have to be bad or unlucky to get hit more than twice.
Sure, you can die if you stay in gibby’s ult, but at least Gibby has a ton of warning. Plus, you’ll probably won’t die from it, just take a lot of damage.
Sure, you can throw 3 grenades in an enclosed area to get the effect of a single gas trap, but if you consider that the gas traps actually block things and also are more available, it would be op if 1 gas trap had the same strength as 3 regular grenades.

Caustic has way different mechanics than other ults. His gas has very little warning upon activation, it does damage every second and cover has little effect on it. Other ults, (40 damage a hit ults for example), have plenty of warning, time to escape, are affected by cover more, and don’t actually completely deny the area.
Let’s put this into an example. You are in a place, (doesn’t really matter where), and a Caustic ult is thrown at your feet. You notice it, but by then the gas activates. Your squad scatters, but with only 3 seconds to escape, (because it does 35 damage a second), you either barely escape or die. Most will die. This is op.
Another reason other ults do more damage is because they affect shield as well. Caustic’s gas goes straight to health, and will ignore all shields. A Gibby ult will destroy your body shield and then your health, which gives you more time and a better chance of living.
Let’s run through that same situation again, but with a Gibby ult.
You are in a place, (but this time out in the open with no roof, because Gibby ults will be stopped by any cover overhead), and a Gibby ult is thrown at your feet. Your squad scatters, but because of the amount of warning, you either escape or you get off with only 40 damage taken.
Let’s try it with a Bangalore ult. Your squad is in a place, (again with no ceilings or overhead obstacles). She throws her ult down, (not at your feet), and the missiles come down. Your squad immediately runs away or gets behind cover, with most of you getting off without any damage, maybe all of you if you’re good/really focus on running.

Granted, there are times where people are trapped or can’t otherwise escape, but even then there is a decent chance Gibby and Bangalore ult won’t kill them. (Gibby will definitely get them low, unless there is cover. Bangalore usually can’t kill, plus it’s really stupid if you get hit 3 times by her ult in one go. You’d have to be standing in a terrible place.) In that situation, that Caustic buff would be even more op, as anyone caught in there without a means to escape will basically 100% die. There is very little you can do.
Caustic gas is good for area denial. If someone runs through it, laser them. They’re practically blind, highlighted to Caustic, slowed, and taking continuous damage. Sure, someone can run through and live, but you shouldn’t be letting them. The gas gives you a big advantage, you should use it.

In summary, three hits of Gibby ult and Bangalore can kill you if you have low health, but both are affected by obstacles more, Gibby ult won’t for sure kill you, there are a lot of blind spots, and Bangalore ult simply shouldn’t be killing you. Whereas Caustic ult will kill you in 3 seconds flat (no matter what shield you have), is affected much less by cover, will 100% affect anyone in the radius, and also as a bonus slows and blinds the enemies.
Also, having a single gas trap have the same effect as 3 grenades is op, as you can throw down 3 gas traps at once, and they come back over time. That’s about the equivalent of 9 grenades, and if you camp you can get up to 18 grenades worth of traps. (6 traps)