Put a vendor for CoF with unindetified uniques for a price of 50k gold each and ascendance runes also 50k each. Make the unlimited stock so when a player buy and item, it is still there.
MG is the one that needs a gold sink, not CoF. Lightless Arbor and stash tabs are already gold sinks for CoF.
CoF also needs mroe gold sinks. Especially since they halved stash tab prices, which still boggles my mind
Sure, but LA already works as a decent gold sink. You can get plenty of useful stuff from there (especially rarer runes). It’s just not really worth it for MG.
We could argue that LA could use a boost, or let CoF ranks affect it, or even that we could have another mechanic that competes with it, but I would rather have a more interactive gold sink than a simple slot machine.
EDIT: Also, if you were to implement something like this, the costs would most likely be 500k instead. Otherwise you’re just watering the unique pool and making all uniques accessible.