banana priest

so it's a small sample size, but might be viable if more people want to work on improving it.

the goal is to make a bunch of spells in your hand from spellkin, wandmaker, and banana vendor, reduce them to zero with palm reading or nazmani bloodweaver and then go off discover cheap spells and play cheap spells or play cards for no mana. you can clone the nazmani with a gift of luminance to play all your spells for negative 2 mana. 

you can tutor your minions with insight, effectively allowing you to fetch for 0 mana when corrupted, and you tutor your spells with cleric of scales.

don't be afraid to tank damage to face because you have high likelihood to generate radiance or renew from spellkin and wandmaker.

as a bonus, you'll eventually finish the g'huun achievement.

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i've thought about slotting in c'thun the shattered as a finisher, but you don't really have enough card draw. you mostly have card generation, which is similar but different. you might try change the onyx magescribes for gadgetzan, but then you only have 4 dragons for cleric of scales, which is already thin at 6 dragons. but it's an option for someone to explore.