Anoints are cool in general, and has a lot of potential to expand even further, but the one major flaw with them is that they make legendaries more or less useless unless rolled with the correct anoints on them. This is why it would be a fantastic endgame idea to add something like this. Being able to run through a tough raid with loot and everything, but also have the reward of being able to reroll your anoints on a given item after beating it. Possibly 3 rerolls per completion.
Not only is this endless content, but also a great way to make any legendary an item with potential, and not just a piece of garbage left on the floor like the thousands of other legendaries that are left inbetween that one decently rolled one.
There are pretty much no downsides to this. It’s not going to be free anoint rerolls put behind a lazy idea such as some machine where you pay currency to reroll it and it’ll give people something to do with every item that they’re trying to get for their build.