Rare/Common Only Budget Dark Wisp
If you have them the following epics are possible additions to this list:
Three Wishes, Ruunins Presence, Aurora's Creation, Altar of Souls, Twin Soul Spirit, Soul Eater and Yak Attack.
Try to get your Devouring Plants setup like this https://i.imgur.com/PXRlrOu.jpg . The AI doesn't know how to play around it and just throws it's creatures into the death trap. Buffs might seem odd in a creature less deck but they help you make the most of the creatures you do have and pro-active cards that aren't creatures or creature generation are few and far between.