The card construction mechanic is such a great gameplay device, and the fact that you only gain cards by defeating enemies (other than the card you gain at the start of a round) makes for some beautifully painful decisions! Highly recommended!
This one might be favourite of the 3 (Wingspan, Wrymspan & Finspan). My 8 year old son can play this game with no problem, and usually beats me - yes, I try to win - he gets all the good cards ;-)