Oh, hey, is that Rise of the Bloodborn, the second expansion to free-to-play card-battler Duelyst [official site]? We didn’t see you come in. Oh, what’s that - you snuck in through patch 1.78, which went live a couple of days ago? Please, make yourself at home. I'll just tidy up a bit while you get settled.
Rise of the Bloodborn adds 39 cards to Duelyst, which is a pretty weeny set compared to the hundreds we're usually used to. But these cards aren't picked up by grinding through orbs (card packs in Duelyst speak) for months - oh no, these ones cost three times more than normal but contain three copies of three different cards, and you'll never open that card again.
So, with 39 cards and three cards in a pack, you'll only need to open - get your counting fingers ready - 13 packs to get the whole set. Or you can just plonk $20 down for the whole set and save yourself the effort of counting.
Some of the Rise of the Bloodborn cards also comes with a new mechanic, known as Blood Surge - which let other units get a unique effect - such as restoring health, teleporting around the arena or dealing damage - every time you use your Bloodborn Spells. That's a pretty interesting new twist, and one which will hopefully see better results than when Hearthstone introduced its similar (and still largely unpopular) Inspire mechanic - you can take a peek at the full range of cards over on developer Counterplay Games' page.
You can read more about Duelyst in Matt's Wot I Think.