Normal spiteful priest, but with LIW and a bunch of dragons. good for mid-late game. Try to survive early game using taunts and heal.
THIS DECK IS MOSTLY LATE GAME so try and maintain control of the board with Duskbreaker and try to cheat out lady in white as soon as possible. The amount of late game minions and spiteful summoners can make you hard to beat mid-late game. If your opponent is shaman, ...well... kill him/her as soon as possible b/c you don't want 10 minutes of battlecries.
Prince Keleseth: value two-drop, preferably not replaced. Its a must-have in a lot of deck including spiteful druid and tempo rogue. I would suggest you craft it but it can be replaced by taking out several high-mana cost minions and adding in 2*Shadow Ascendant, Acidic Swamp Ooze(if you don't have Gluttonous Ooze) and/or Squashling.
Primordial Drake: really good with health and dragon synergy, and offers a board clear at the same time. I suppose Witchwood Grizzly,Sleepy Dragon, Mossy Horror, and The Lich King are suitable replacements.
+120 upvotes for specific opponent class guide
If you have any suggestions of how to improvise the deck, please comment below or message me. Thx!