That's 21 seconds IF you perfectly level up. Ideally, you will have it for 20 seconds. I've already made my case why venom is flawed. Level 2 is too weak. You're pretty much always going level 1 or 3 unless momentum is on your side. And when you get to 2, the risk isn't really worth the little bit of extra damage. And if you cannot gradually level up, then the trait becomes inferior to other character traits. I'm just stating what I think needs to be adressed in future patches.
Remember that because cinematics force traits to cooldown, you can be at level 3 and they just clash and now you're stuck with level 3 cooldown. I'm fine with that if venom were stronger.
It seems like the consensus so far is that level 1 is the best, level 2 is lacking on sufficient bonuses (my opinion), and level 3 has too high a penalty (since everyone wants to avoid it).
Level 2 honestly isn't that bad, it provides only 25% less than the level 3 and takes about 30% less overall debuffing for 3 seconds less of a cooldown. Its still ample damage, and you can mid-screen stall off of a read to get your cooldowns off.
Personally, and once again might just be me, but if you hit level 3 and they clash, its not like you don't have the same option of clashing to remove your cooldown. Its a give an take, you might lose one dose of level 3, but you also have the opprotunity to run 2 doses of level 3 back to back. When you are dealing in the area of 50-60% with one correct read of level 3, the match could be over before you know it. Likewise, the clash damage and healing are staple, being they aren't affected by venom cooldown. Level 3 venom cooldowned 3 bar clash does 30% no matter what. Mighty helpful imo.
In my honest opinion, I feel people act the wrong way when venom is on cooldown. Standing back and letting your opponent come to you with those damaging combos is NOT the correct way to do things, and I'll go on record to say this. You have much more chance of surviving if you stay on them. You lose your armored options so, of course, you have to be more careful. However, with those grab set-ups and the huge amount of time you can stall using combo boosters like MB double punch and MB command grab, you are more likely to prevent more damage from being dealt to you over trying to keep a distance against people whom you need to stay close to. You having such reduced mobility will end up hampering your ability to fend them off, so cutting 7 seconds off of their time to take advantage and off of your disadvantage for landing a b.23 midscreen, or all of it landing a b.23 at the corner of the screen is worth it.
In my opinion, since I don't judge on whats "best" for a player (differing styles), I'd say level 1 is getting in, level 2 is getting damage, level 3 is getting kills. 125% is hefty damage and the cooldown and duration are sufficent to fit your needs. You'll be dishing out more or less 40% combos using level 2, which is more than enough. Level 1 gives you that armor, and level 3 is just when you know you have the option to end things out or clash to refill the juice box.
I think his venom trait needs some minor tweaks/improvement. Here are some things I don't like about it and why:
It runs out during animations and during the resetting of a round(Clash, Level Transitions, Being Supered etc)
I don't like that during an ended round resetting my venom runs out, it is unfair IMO. Supposing I made really good reads and was punishing my opponent hard, I feel that while the round is resetting, I shouldn't be punished for my efforts by having my juice run out and making me vulnerable, especially if I took the risk of going to level 3 and it paid off. This gives the opponent the upperhand at the beginning of the next round, and if they are zoners with good range and multi hitting projectiles even more. You will start debuffed and will have to be extra careful since you take more damage and chip and lose alot of mobility.. This ruins the momentum you had going in the previous round and rewards the other player and punishes you. I feel that it should stay where it's at during the round ending animation. The same could be said for stage transitions etc. If you have venom and are trying to start offence and by any chance you get hit with a super or w/e and cannot buffer another venom dose because of the animation the other character gets alot of free xtra damage and can wreck you for free.
I also dont like the severe debuff/penalty of going to level 3. It may give a big boost in damage but remember it runs out quite fast. Not only is your mobility affected you take a huge chunk of extra damage from the opposing character and you can barely dish out past 12% of damage. The opponent will abuse this fact if they know you went to level 3 and destroy you while you're in turtle mode. We're talking about a character that doesn't even have projectiles to begin with in a game that favors zoning and characters have ridiculous projectiles that can cover the entire screen. And yes he may get 3 hits of armor for level 3 but remember, you still take damage while you armor through peoples stuff. The only upside I see to it is the buff in damage but the risk is too high for the reward. So that leaves us stuck using level 2 or 1 most of the time which aren't as effective. I don't know how they could rebalance it or tweak it but at the moment I find his trait flawed. essentially i think Doomsday can do what Bane does but even better.
As said, you can use these to erase your cooldown as well. Its not always a one-sided street, you do have options too.
At the end of round 1, if you popped level 3 to bump off their grey and don't have a clash at your disposal imo you are being wasteful. Its not a risk/reward type system, its a pay-to-play system. You decide to offer up level 3 knowing the risks instead of using something like level 2 and just making that one more read, and with no clash cleanse thats a matter of whats called "instant gratification." Instead of wanting to chance getting that read, you decide to just max out and go for broke. In poker, blackjack, and the like, you are always better off keeping some chips off the table both for the sake of yourself and the opponent. Going all in shows either overconfidence to which the opponent can fold, or despiration which the opponent can take advantage of, where as saving some chips tells the enemy a lot less and gives you a back-up plan should your hand not succeed. How much are you willing to pay in the long run to make that play now?
To be completely fair, and it may just be character bias, but Bane without that massive debuff would be a sight overpowered. At level 3, for 6 or 7 seconds, we have damage output higher than anyone else in the game from anywhere on the screen, armor on all of our supers, projectile immunity (which means no, you don't "take damage while you armor through people's stuff" if that stuff is projectile based.), and above that we are nearly meter independent with the option to instantly clear that debuff and go back into that mode. That mode exists literally for hardballing the opponent, its not a damage form so much as an ender form. I mean we do damage equal to some characters supers without even having to burn meter, its a fair trade-off that if you are using that kind of power recklessly that you take the bite from it. The mobility debuff I can agree is a bit excessive, but the rest of it is fine. Its very relatable to the character itself, as careless misuse and dependance on that huge amount of venom ends up becoming Bane's downfall in more than one occation.
Level 1 and Level 2 are fine in that they serve their purpose, being 1 giving you armor to stay in and 2 giving you a fair amount of damage and an easily managable cooldown. Too many people are comparing 2 to 3 as though they serve the same purpose, and they really don't. Level 3 isn't made to do combo damage, its made to end games. Level 2 is made to work into combos, since the debuff is much much much less than level 3 will force you to endure. I find his trait to be pretty good, though as I said the mobility debuff is a bit much.
Still, for the meter independance he brings and the amount of people who can't wake-up against him, I don't think theres really much reason to gripe about his trait. Now if we could get something like say a properly working super that doesn't randomly trade with people who so much as break wind when we go for them, that would be a good deal. But his juice box is fine, people just need to learn to manage it better and not treat it like a problem solver. Also Doomsday does our job even worse, since he doesnt have access to super armor on all of his specials, reliable high/low mix-ups, or an unblockable super. His trait isn't all that great, his super isn't that great...
We grab through Lex luthor's maxed out trait armor, which is supposed to be incapable of being hoisted. We grab through just about everything, honestly. And projectile immune at level 3? We get the one-up on the entire cast who get shut out of our supers via deathstroke machine guns.