No... it’s be better to nerf her base damage then. Since the base damage maxes out at 260, which is pretty high. Beefing it down to say 220 would’ve been not only a smarter move for her, but a healthier one as well.
To prove my point let’s do some math
Tank karma builds maybe 1 AP item top lane, that item usually being
if any item at all (Though she usually rushes iceborn, I’m just giving you the FULLEST benefit of the doubt). ROA gives up to 100 AP, which means currently it alone gives her 60 extra damage on her Q. With this nerf it gives her 40 instead, wow... 20 whole damage less. That sure does hurt tank karma a lot. And remember this is assuming She even builds ROA.
But wait, what about Soulflare? Her ulted Q? Surely THAT would have a lot less damage. Well let’s see, assuming you stand in both the initial explosion and the second explosion, the AP ratio totals out to be 150% meaning it deals 150 bonus damage and with the nerf it’s.... 130... wow 20 less damage......
yeah there’s no way to try to sugarcoat this. This nerf is a way to gut support and Mid Karma for worlds. If anything Tank Karma was nerfed the least of all her play styles.