Nice game, it would be nice to see the pack chances maybe trough an upgrade or update or so.
Can't wait for the full game.
I'm glad to hear you liked it! :)
Packs have one guaranteed card of their own rarity (except the Legendary pack, which is 1 Epic + 1 Legendary guaranteed). This is displayed in their tooltips, both in the Pack Trainer and the ingame shop. + a small but undisclosed chance of being upgraded to the next rarity.
I hope this helps!