In my dream it went on armor pieces and each item was a 3% boost, so the max was 21% timer length increase which would add about 3-5 seconds on most abilities, and probably just a second or 2 on debuffs. Now that I'm awake, lol, I think it makes more sense to have such a trait on weapons instead. I also wonder if it should have a downside, such as during the extended period the power of any effect is also reduced by the same percentage of time it was extended. So if someone has abilities that last 21% longer, those additional 5 seconds are also 21% weaker than normal. Maybe this would be too many calculations though for the game to run.