Anyone with heal block can work; Sentinel, ghulk, yondu, champs like that. Lots of champs who can counter it, even without petrify. Warlock destroys anything with regen if you have him already.
Also with vigor, you can out-damage it without too much difficulty, depending on how powerful the opponent is. Domino, ghost, omega, anyone with big damage could work. For example, I've been taking out the Act 5.4.6 Ultron boss with ghost because she can just out-do the regen.
Another tactic I often use is to bring in a nullify champ, especially SS. Clair voyant and SW can work if you get lucky as well, but SS is the best. The buffs only make him stronger
Lots of other counters out there, but those are the ones I can think of off the top of my head
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Also with vigor, you can out-damage it without too much difficulty, depending on how powerful the opponent is. Domino, ghost, omega, anyone with big damage could work. For example, I've been taking out the Act 5.4.6 Ultron boss with ghost because she can just out-do the regen.
Another tactic I often use is to bring in a nullify champ, especially SS. Clair voyant and SW can work if you get lucky as well, but SS is the best. The buffs only make him stronger
Lots of other counters out there, but those are the ones I can think of off the top of my head