the NPC challenge level is fine ( Since once you got the card you won't be challenging them so it makes it semi-fun and a change to vs a random / roulette npc ) only problem is with RNG you should be-able to ' turn-off ' a card you already have so you can't get it any more or boost MPG card values 5-6x. Personally I have all the NPC cards that was the FUN part sure some of them dropped after 100 - 400 wins * the windows make this hell for some * but the RNG of dungeon drops / Booster drops are just horrible, the ones you want are so rare + queue times.. + dungeon times.. can take 2-3 hours just for 2 runs * WoD is horrible * they need to make every card able to get in 3 ways.. Dungeon, Npc , Pack.. to make it fun for all.