What you need to do is make them forget how to use the ability in the first place!
Hiii!!!! 👋 it’s me, the girl from before who had to deal with the pesky quicksave hero!
Thank you so much for the advice! It took a bit of work but i managed to cloud his memory of his quicksaves! Then i was able to run the usual playbook — turns out she’d been using that ability to act a lot tougher than she really was! Now she’s one of my thralls. I made her hand over the ability, and now I’ve been promoted! I’m not an imp anymore, see? Now I’m a full fledged demon! Not as high a rank as you are, I’m sure, but still wayyy too sexy to waste!
Also, uh, me and the thrall and my imps have a new problem. Turns out she had a brother in arms? And he’s trying to ‘rescue’ her from me with his own bullshit ability. He doesn’t do time manipulation, but every time i get him useless, some sort of passive cloning spell happens, and there’s a new well-rested uncorrupted additional version of him! It’s so ANNOYING!
Any ideas what to do with a ‘respawn’ hero? For now I let him drag the thrall back to an inn, but I can’t figure out how to make the corruption stick! Ugh! I don’t wanna waste my thrall’s reveal so I really need ideas quick, if you’ve got any?
Congrats on your demonhood! That said, you might have gotten yourself in a great deal of trouble, so listen closely if you don't want to get slain so shortly after finding your true demonic self
There are two kinds of respawning abilities (ability isn't really the right word for it, but it'll suffice for the moment): limited respawning and unlimited respawning.
Heroes with limited respawning are pesky, but manageable. They have a set amount of "lives" they can go through before they stop being able to remake themselves, like some kinds of feline adventurers, who have 9 lives. Which means that, if you keep overpowering them over and over, they'll just run out of lives and fold eventually.
That said, it's still a powerful ability, because they accumulate experience and power between each respawn (which is one of the big advantages of respawning over quickloading), so you should consider retreating and asking for help if you feel you're becoming outclassed.
Scholars are not exactly sure about the inner workings of limited respawning, because it's an incredibly rare power, and usually seems to have very specific conditions and rules that doffer between each case.
We demonesses actually have a power that resembles the limited respawn, because when slain we can draw on the power of mortal souls we've absorbed to resurrect ourselves, which is why you need to be extra careful: you've only acquired one hero's soul so far, so if you're slain, either it'll be permanent, or you'll go back to being an imp (I haven't encountered this particular situation before, so call it an educated guess)
The real problem is if you're dealing with an unlimited respawning hero.
You see, respawning works a lot differently to quicksaving and quickloading. On top of carrying over experience, you can't make them forget how to do it or block off the skill with anti-magic, because the hero doesn't actually control the ability at all, it's caused by outside circumstances.
If the hero you're dealing with has unlimited respawning, you might be dealing with a god's chosen, or a prophetic hero. If it's a prophecized hero, you should consider grabbing your thrall and leaving and hoping the hero gives up on her, but if he's gone to such lengths to get her back, it might be the case that your thrall is fated to be an ally in the prophecy. That one... Actually has an easy solution, now that I think about it. You could let your new warlock go on this adventure and finish the prophecy with the hero, then go and get her back, and since the prophecy is over, fate isn't going to rewrite itself to save the hero anymore, so you can corrupt him no problem! We demonesses live forever, so the quest will likely only be a short while relative to your lifespan!
You could also try breaking the prophecy, but that would require you to 1. Know what the prophecy is, and 2. Actually alter the events in a way that fate can't ensure it's continuation, and that's hard.
A god's chosen is a different beast entirely, but considering you already managed to defeat them a few times, I thankfully doubt this is what you're dealing with. Divinely chosen heroes, on top of respawning, are on a completely different level to regular adventurers and heroes in terms of power, even I would be reticent in contending with one.
The best way to deal with a god's chosen is by making their deity abandon them, or making them abandon their deity. The former typically means making them act in a way that is contrary to their gods' wishes, for an example, enticing them to willingly break a vow of chastity, the latter would require you to have a convincing enough argument to make them abandon their faith. Neither of these options are easy, mind you, but if you have a god's chosen hero pursuing you, you have to try every tool at your disposal.
Otherwise, you'd have to kill the deity powering them, and darling, that's far above my paygrade