Love the build! Kestrel is. MY far my favorite hero at the moment. But the cp side that she has is amazing! Her skill show procs any on hit effect! You build is good, but only for damage. She's a stealth her like taka, but with less health and defence it seems. My build for Kestrel right now is Shatterglass, Broken Myth, and alternating current. No you may ask why alternating currtent, but if you read her skill shot, it reloads basic on attack speed. And if you don't know already her energy...

I find that aftershock and alternating currents with your core works extremely well.I start the same early game tank then work towards those in the end. I also max my a and b tho. Ult is good but if you run contraption and aftershock you can have a 60 sec cd and 9 sec cd on vaingaurd and 13 sec on punch.