Ares 70016 is a tool which "grabs" a stud - and in the process of removing the stud, actually "tightens." Think a jacobs drill chuck which works in reverse.
Can be used either with a socket wrench, or can be used with an impact wrench.
I find it works best with the impact, to the point of like 20 minutes to remove a head stud using a pipe wrench/pb-blaster/and a small hammer (vibration helps the PB Blaster and break the rust-bond) reduced to like 2 minutes/stud or less without anything else but the Ares Tool/impact wrench.
I was like 2 hours to remove 4 studs with the old method - breaking/ruining two - to less than 20 minutes to remove the rest of the studs. And they all came out "usable" with minor clean-up.
It works certainly by putting "lines" into the stud - think a pipe-wrench - but the lines are "linear" with the stud and don't reduce its strength. Even across the threaded portion. And the threaded portion when cleaned up with a thread reformer (best) or a die can be used again.
I bought this one from Amazon - probably the best price out there and I had Amazon Prime so shipping was already paid for (no free shipping with Prime, just paid in advance.)
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I can't speak too highly of this tool.
Joe K