So Wretched Reclaimer walks into a bar.

The bartender asks Reclaimer: "Welcome! What'll you be having?"

"One Whiskey, on the rocks."

 "I'll have what he's having", a hooded figure says from Reclaimer's right.

Reclaimer looks, and the figure lifts its hood to reveal long blond locks and startlingly scarlet eyes. 

"The name's Shadow Madness. Have I seen you around before?"

Reclaimer cocks his head, letting a mischevious half-smile play across his lips, the mark of a card who knows he's the shit of Johnny's dreams everywhere. "Why, I'm not quite sure. Are you flirting with me?" He asks. 

"O-ho! Straightforward, aren't you?" Shadow Madness responds. He tosses his hair back and grins, displaying long, sharp, pearly white teeth. "How could you tell?"

"You and I are both 3-mana. Of course I'd know."

"Well, I'm flattered you took the time to look me up."

"Didn't need to. You're the talk of the town, you and your new mana cost, eh?"

Madness recoils in mock horror. "Is that a problem, good sir?"

"Why no, of course not. I think it looks quite nice on you."

"Oh yeah?"

"I think it'd look better over at my place."

"Oh yeah."

Rationale: Why do these card belong together in a deck?

Every good deck guide needs a good deck intro, they always say. Anyways, with the new Priest class rework, Priest has several juicy incentives to play with attack altering effects to steal cards. Key to this strategy is the new Scarlet Subjugator, which for 1 mana reduces enemy attack by a fat 2, and makes comboing with Shadow Madness, Forbidden Words and Cabal Shadowpriest a cinch. 

To up the stakes with these new cards we introduce Wretched Reclaimer, which is a really cool card that never saw play. However, when paired with our temporary steal effect of Shadow Madness we can keep the minion for ourselves, and even take a potential solid value trade. It also has synergy with other steal effects - most of the attack lowering effects last until our next turn, but resetting the minion with Reclaimer gets rid of this drawback.

Also we actually want to win occasionally, so Galakrond is in here too.

Attack Modification Package:

2x Forbidden Words

2x Lazul's Scheme

2x Scarlet Subjugator

2x Shadow Madness

2x Wretched Reclaimer

2x Cabal Shadowpriest

Lazul's scheme and Scarlet Subjugator are our primary attack reducing effects, and due to their costs they are easy to combo and work synergistically with the other cards here, those being Lazul's Scheme, Shadow Madness and Cabal Shadowpriest. It kind of hurts to have to Forbidden Words a minion whose attack is already reduced, much like how you don't want to kill Frozen minions, but Forbidden Words is kind of a generally good card, so don't pigeonhole yourself into only using it with synergy.

Wretched Reclaimer acts as a sort of reset on a lot of the effects we'll need to put on our opponent's minions in order to reduce their attack. For one, Shadow Madness is only a temporary steal, but if we reset the minion we steal with the Reclaimer that debuff goes away and the card is ours. Our attack reducing effects all last until our next turn, so even if we steal them they might be really weak and susceptible to being killed. Luckily, Wretched Reclaimer also gets rid of this effect, making our stolen minions nice and beefy again.

Galakrond:

2x Disciple of Galakrond

2x Shield of Galakrond

2x Time Rip

1x Kronx Dragonhoof

1x Galakrond, the Unspeakable

*Search Galakrond*

*Insert*

Except the 4 mana guy, that guy sucks.

Good Priest Cards:

2x Penance

2x Thoughtsteal

2x Breath of the Infinite

1x Mass Dispel

1x Shadow Word: Ruin

2x Plague of Death

This is to keep us alive and get us our Galakrond and good combo cards. Shadow Word: Ruin and Mass Dispel are tech slots, run whatever you want. 

Also, Thoughtsteal is a good card. Yeah, I said it.

Conclusion:

 And then Shadow Madness and Wretched Reclaimer lived happily ever after.