Ive done a version of shadow priest that uses two tribes.
Pirate tribe: Defias Leper x2, Mr Smite edit: added Fogsail Freebooter x2
the 2 mana priest pirate is amazing and coupled with Mr. Smite you can do 6+5 + 5 = 16 damage from hand for 10 mana. Mr. Smite also works well with Amaglams which in turn can find you another Mr. Smite or the priest pirate.
Works well with all the spells that you cast. Handmaiden refills your hand while Crushclaw allows for more naga draw (which is crucial so that you can power up them with spells). Treasure choice from Queen depends on your hand. If you need refill choose the spells and draw, If you have cheap spells in hand go for the weapon to finish off your oponent. Baba Naga is nice 4/4 with smite that can go face. Valiash allows for some good early tempo plays or big brain finishing moves at the end.
The shadow priest cards: Benedictus obviously DUH!, basically all low cost shadow spells + one Shard, Voidtouched ( she is insanely OP both at turn one and the turn that you want to finish you oponent), Needle - works well with Voidtouched and all the low cost shadow spells, Deceptor for spell draw - without it i found that i missed that last one shadow spell in hand to activate stuff.
Shadowed Spirit is for those akward removal for oponent and nice damage.
There! A viable shadow priest. Dont have exact stats but its on the positive side of winrate. The games are fast. The worst matchups are control warrior and druid. Rest is more than winable. You can get oponent to below 10 hp by turn 5-6 easly and then just finish them off. Really fun to kill those mech mages and pirate warriors before they snowball in later turns. Generally the idea is to control board while chipping damage from oponents face.
Give this deck a try, its super fun!
EDIT: CHANGES: - 1x Amulet, - 2x Shadowed Spirit; + 1x Needle, + 2x Fogsail Freebooter (reason for this is that i found the Shadowed Spirit a bit akward to play sometimes and Amulet is almost exlusevly used for its trade mechanic and rarely for resurecting the Spirits. The needle is preforming really well helping with board control and face damage specially with voidtouched so i figured if i got 2 of them might aswell add more pirates supporting them)
EDIT 2: Changes: - x2 freebooters, -1 deceptor - both not consistent enough. Added +1 brann ( lots of battle that we have), +2 slitherspears - not enough one drops and it synergies with our spells