The current Mantra W is a lot more interesting than the latest PBE iteration
Don't get me wrong, a 3.5 second snare is insane and would be very powerful etc, but I really can't say it'd be at all fun to use. The current Mantra W is so much more interesting than that because it's rather situational and there are choices to make with it. "Longer snare" basically just says "use this when you really want to lock someone down" and that's... really obvious and boring.
I don't mind the Karma changes as a whole - the shield thing I'm OK with, buffed passive I'm OK with. I even liked the damage amp/healing thing a lot, that had a lot of potential uses that I was excited to play around with and was unique. But I can't think of much you could have done that'd be more boring than "the snare lasts longer". Please don't let that go live :/ Mantra W is cooler than that live and was cooler than that in the previous iteration too. This is bizarrely generic to the point that I can't comprehend why you'd want it. If you want Karma to feel better to play then making one of her ultimates "snare someone for a really long time" isn't really the right way to go about it.