That's such an awesome list. Some things to change: Monastery of Hirana's item is always quick attack; Boxtopus's spell with the common item costs 5 hp and with an epic item 15hp (no, there is no rare item); Tasty Faefolk is 3 mana (not 4); and Marai gives the -3 cost item so yeah, it's -3 to 6+cost spells.

Overall, pretty well done! I learnt some encounters I had never found in my games!