Any online slots with a wager saver feature?

So, I’m trying to track down online slots that have a "wager saver" feature—you know, the one that lets you zero out your balance in a cool way. I stumbled on one like that about a year ago, but I can’t for the life of me remember the name.

Feels like they’re super rare, too, because I’ve been Googling like crazy and coming up empty. Anybody here know of any slots with this feature? Would love to give them a spin (pun intended). Let me know!