Hearthpwn

Hey, this is a very budget otk priest that can get you to rank 15 and even 10 if you can play it very well.

Mulligan :

Search for Northshire Cleric ; Power of Word: Shield Radiant Elemental

Don't keep 3+ drops unless you are going second

Never keep Wild Pyromancer if you dont have at least 2 spells

Since we aren't running Shadow Visions in this deck you may want to keep Divine Spirit and/or Inner Fire

Expensive Replacements :

-2 Shadow Ascendant  +2 Shadow Visions Shadow visions is one of the best cards in the game, lets you have access to inner fire + divine spirit combo so easly

-2 Tortollan Shellraiser  +2 Dirty Rat, Dirty rat are way cheaper and let you play even vs exodia mage

-2 Sunborne Val'kyr  +2 Priest of the Feast 

-1Circle of Healing  +1  Lyra the Sunshard  Lyra it's almost an auto include in this deck since you have a lot of spells that you can cycle

-2 Tar Creeper  +2 Twilight Drake  This is more a choice than a replacement since you have to choose between having a 3/5 or a possible 4/10, they are both weak to silence but, personally, I prefer running Creepers since they help you against aggro decks

Thank you very much :)