So we were talking on General in Everlasting when we came up with some ideas on the TW/Scrapper issue. Since we know it's getting changed as it is currently OP as hell I thought I would post some of the thoughts here to get some more feedback.
One of the major issues with TW on Scappers is the combination of Mechanics that allow them to do insane amounts of damage in a brief amount of time. This is a combination of the Momentum mechanic, the Scrapper ATO that grats a +50% crit rate and the damage spike and instant momentum provided by build up. My TW/BIo has Gaussians +chance for buildup on my Build Momentum, which means I can get a 200% damage spike, and a +50% crit proc with defensive sweep. The number of attacks I can execute in that time is what makes the overall set just insaine.
So the Idea was to adjust how momentum works, rather than having you hit once and suddenly have the cast times of several abilities reduced to 0, each attack reduces the cast time of your abilities for a few seconds. The effect would stack, say Defensive sweep reduces cast time by 15-20%, then Titan sweep or Crushing Blow reduces by 20-25%. Once you hit 100% you gain momentum and all your cast times are instant for a few seconds then you reset. Basically momentum is something you have to accumulate rather than just instantly given. This makes it much less likely you're going to proc your +50% crit rate at the start of your momentum, but it is still possible.
Another concept is to change the function of Build Momentum, of course it would have to be renamed. But a couple ideas were to have its damage buff reduced but instead have it grant a higher crit chance, say 5-10% for a few seocnds, and/or have it reset the cooldowns on all TW abilities.
Anyway, just some ideas on general chat in hopes that TW doesn't get nerfed too far into the ground.