From my limited testing, this seems a really nifty card. By the mid-game you've probably got resources you want to ditch, such as empty spells like Shrivelling or Mists of R'lyeh, or possibly allies like Arcane Initiate, Alyssa Graham or David Renfield with irritating doom on them that you want to get rid of. Now you can bump them off for fun and profit.
At worst, this is an extra Emergency Cache, but it's best feature is it's flexibility, and it's ability to draw 3 cards. Amnesia or Paranoia just cleaned you out? This can help you recover.
The down sides?
First is that it requires XP - though 1 is reasonable, I think.
Secondly, you need to have an asset to to discard. This is a problem at the start of a game. I would always throw Sacrifice back during a Mulligan. Still, if you do have one early, for mystics icons are usually useful.
Lastly, if we see mystic builds that are very event heavy (Sefina Rousseau) or where they might not want to discard empty assets (Akachi Onyele) then it might not be the card for them.
I think there might also be a combo with Quantum Flux here, too. If you've used all your Shrivelling charges, you can use Sacrifice to push it into the discard pile, and then Quantum flux to pull it back to the draw pile. That feels quite a lot of work, though...