As mostly a CoV3 and CoV2/x main (although to be fair I play pretty much everything at this point), Tormented Thrall likely needs a change. The trick is finding a way to keep it relevant, consistent, and not overly strong or weak situationally. Removing the sacrifice effect and only allowing it to work off of abilities means it will be terrible on a bad opening hand, and amazing on a good opening hand, which leaves it at a very inconsistent and hard to balance state.
A much easier, much more consistent way of leveling its current power would likely be lowering it to a 9/9, or 8/8 even. 8/8 would still be able to fight Kali, Bloodthirsty Dead, trade favorably with Flame Dawn Hound, still block and attack meaningfully versus very early Hermit Tokens, and so on. The issue is that right now, the two relevant 2 purity (and 3 purity) Verore command zones are centered around Rubble Golem and Tormented Thrall, and most of the other current 2 purity or greater Verore command zones are not particularly viable in comparison. Nerfing Tormented Thrall out of competitive play will simply make CoV3 Burn and CoV2/GI switch to Rubble Golem, which isn't a good solution if we're looking to give Verore more interesting command zones.
It is definitely a card that is the subject of a lot of debate at the upper level currently. Part of the issue can be summed up by explaining that it is that is is mostly on curve on turn 2 with other decks like 3GI, but due to its design and pacing in 3CoV and how many you can reliably run (2 in command, 3 in deck), on top of the fact that its effect can be triggered for no resources, creates an awkward situation. Early game, it trades with Infected Drone (And dies to Support Drone/Aleta Tinkerer combo), as neither can be played until turn 2. However, Mid and Late game, it is a 10/10 for 2 very consistently, which is very, very strong in Infinity Wars regardless of the faction in question.
Its current power helps to push one of the strongest purity combos in the game (CoV2/GI1) from top tier to questionably overpowered. It is autoinclude in all 2CoV decks currently and is a game changing draw in the early game. It allows you to play very aggressively with strong aggro characters as a faction that, as far as I understand it, is designed to be played as a more mid to late game Ability oriented faction. It definitely needs to be looked at, but the adjustments to the card need to be handled very carefully.