In short: Lethality sucks.
There are two specs Lethality can be compared to: Concealment and Firebug.
Concealment offers more crowd control and allows the use of Hidden Strike. With Corrosive Grenade used for area damage there will not be much time to use stealth in pvp thus taking Hidden Strike out of the rotation. Acid Blade does almost as much damage as Corrosive Dart and increases armor penetration. Overall Concealment does more damage, suffers less energy problems and offers a simple rotation. Effectively TA and energymanagement is something the Concealment OP doesn't have to worry about.
There are simple changes that would improve Lethality gameplay:
- adjust the dot-damage via talents
- rework Cull so that it doesn't need TA anymore or give us a way to gain TA other than Shiv.
- Shiv is useless because we don't get any armorpenetration. We need Overloadshot to be "our" Shiv
- Weakening Blast is by far the worst 31 points talent. The damage done is too low. The 30% more dot-damage still don't make our dots viable.
- Lethality could use a range increase to 15 or even 20m to make up vor the lack of defense (Revitalizers)
Concealment gets: Laceration, Acid Blade, + improved Back Stab + Improved Hidden Strike
Lethality gets: Corrosive Grenade, Cull, Weakening Blast yet no improvement to key melee attacks (Backstab, Shiv)
It would be easy to improve Overload Shot along the way to make this spec focus on the gun rather than on the vibroblade. Overload Shot is not used by Concealment because it doesn't do enough damage and there is no place for it wihtin the rotation.
Corrosive Dart should do as much damage as Hidden Strike, Backstab (Concealment's version of these abilities) if you play a Lethality OP.
TA could be linked with Weakineng Blast and Cull should regain TA if used on a target affected by CD or CG same as Lacertion.
