if you are looking for regen debuff, then longbow are the only real option, the cataphract has a really short charge attack which has a 30% chance for 30 second -500% regen debuff
in tests done it can maintain -500% to -2000% regen on a target allowing the longbow to effectively solo rikti pylons
the pure dmg method can work too, but only when the dmg is effective, fighting something extremely resistant to lethal dmg would negate cimerorans or tier 9s such as unstoppable, this is where -regen would beat it out and has an advantage
I've felt for a while that the only thing my Fire/SD scrapper needed was the ability to debuff regeneration in GMs and AVs in order to take them down. He's pretty loaded with purples, PVP recipes and other goodies, so he's well equipped for such a thing. For my Lore pets I decided to go with Vanguard for Twilight Grasp- reasoning that the sorcerer would also be doing a variety of damage types with her several attacks.
However, I seem sort of underwhelmed by the Vanguard pets. They're T4, but the magician doesn't seem to use Grasp all that often and the sorcerer is fine, but they just seem sort of lackluster. My question is: for GM/AV takedowns, is there a better pet for -Regen? Barring that, should I skip trying to -regen entirely and just go for "moar damudge"? If that is the case, I understand Cimmerorans and Warworks are top of the heap?
Any feedback would be much appreciated!