A few people I've spoken to said they've found Cupellation a hard card to evaluate, and as one of my current favourite cards I thought I'd give this card its first review and suggest how it can be used for fun and profit.

First, for general knowledge and lore purposes: What is Cupellation anyway?
Cupellation is a metallurgical process used to get precious metal out of base ore - basic refinement for getting the gold out of impure material (and has also long been a part of alchemy, making it part of Mercury's whole deal), and as a program it does the same thing - it refines the quality of your runs.

Speaking of playing criminal, few things feel quite so on-brand as literally stealing your opponents cards - I like to have some fun with it, saying "Yoink!" or something to that effect. It's a good time, just remember to give them the card back. Unfortunately however this is a hard slot in most crim decks, as the "utility program" slot is usually Cezve - most people identify this card (I think correctly, though some crims getting lots of central access could look at it) as another trick in a flexible shaper toolkit - RwR has been highlighted as a very good set for Shaper, and I think Cupellation is small but useful a part of that.

But I'm getting ahead of myself - how do you use it? Personally, I consider the first half of this card as an (un-purgeable) half-Imp - best used for taking out cards you really don't want the corp to have. Taking away a Seamless or Punitive from HQ or R&D is always good (and like Imp, Cupellation works on multi-access), but it can also be used for removing high trash threats, critically without putting them in Archives where they can be easily re-installed, nor without triggering the condition for nasty reprisals.

Once "loaded" with a stolen card, then the other part of Cupellation come into play - its multi-access. Cupellation's additional access is one credit more than Legwork, but staggered over time (which is thhe same inf cost), for the same number of extra cards, except it can be combined with other run events (such as Legwork, but the possibilities are endless). This aspect I think is under-explored, but very powerful - it is only triggered on the access phase, so even if your run is ended by a rogue Anoetic Void or Border Control, you still have it the next time you get in.
It will depend on the game if holding a corp's key piece away where they can't reach it is more valuable than a Legwork, but the joy of Cupellation is you get both options - a Hail Mary Legwork when you know the game is over at the next turn. For the cost of 1 run and 1 MU, you have a Legwork you don't have to hold in hand, and once Dawn comes I foresee this card getting a re-evaluation as the Imp and Legwork halves of this card do two things in one slot of the cardpool.