"Davriel is a domineering figure with a pencil mustache, dark slicked-back hair, a black suit, a fluffy shirt, and violet cravat. He is known as the Lord of the Manor of the small town of Verlasen, but at the nearby priory he poses as Lord Greywater. In public, he wears a charmed cloak and mask to obfuscate his features. The deep black cloak has a distinctive ghostly tattered bottom — like the frayed spirit of a haunting geist. When it moves, it leaves faint smudges in the air, obscuring his exact position. The golden mask is manufactured in a demonic shape with large dark eyes, sinuous lines, and a gruesome mouth reminiscent of a jaw with the skin removed. Davriel uses a walking cane, with a sword hidden inside.
Davriel is considered to be lazy and selfish. He is able to steal spells from the minds of other wizards, and keep them available for a limited period of time. His eyes change color whenever he uses one of these spells."
There are 20 uncommon planeswalkers in War of the Spark. They all have a static ability and a minus. These uncommons don't have a plus loyalty ability, nor a bigger ultimate minus. For Limited balance, these uncommon planeswalkers are purposely weaker. Their minus effects typically aren't "worth a card" in value.
Well, there's one planeswalker in War of the Spark that clearly gets a card's worth of value in the minus.
Davriel instantly trades for a card from the opponent and then puts pressure on them to rid the planeswalker. This may lead to an awkward attack from the opponent if you have any blockers. At minimum, Davriel will save you some life points if the floor scenario occurs of immediately dying in your opponent's next combat step. Replacing itself and making your opponent's next combat more difficult is a solid floor.
The ceiling? The opponent has discarded two cards and is now dying to Davriel's static Shrieking Affliction or you've gotten a smooth three-for-one by ticking down three times. Davriel naturally dying through the progression on minusing can be a good thing. It means you can slam down a second copy and really nuke your opponent out of resources.
Davriel, Rogue Shadowmage seems like a nightmare for control decks to deal with. Bleeding them out of cards and attacking them on a noncreature axis is a formula for success against decks packing multiple copies of Cry of the Carnarium, Moment of Craving, and Kaya's Wrath.
I expect Davriel to be a solid role-player in Standard sideboards for quite a while. Right now Kaya is the go-to three-mana planeswalker threat to quietly sneak in through countermagic. Davriel will haunt their dreams.
Now let's talk about why you're really here…
Davriel loosens up mana restrictions. 8-Rack loves its colorless lands, but even with four Urborg, Tomb of Yawgmoth, you sometimes don't have access to double black when you need it.
Wrench Mind has been a necessary two-for-one in 8-Rack. It's particularly bad against decks packing artifacts, like Mono-Green Tron, Hardened Scales Affinity, and Whir Prison. Davriel offers the two-for-one or better than 8-Rack needs. I still like Wrench Mind and have assigned a copy to the sideboard for when it's really good.
Liliana's Triumph is an upgraded Diabolic Edict that's also perfect in a deck naturally running four Liliana of the Veil. Ben Friedman touched base with Liliana's Triumph yesterday in his spotlight on it.
"Each opponent" means Leyline of Sanctity isn't a problem. If Liliana is active, you now have an instant-speed discard method reminiscent of Funeral Charm. Davriel and Liliana's Triumph both provide multiple effects that you were already looking for in 8-Rack, which really smooths out draws and gives you more consistency.
It's quite possible that it's correct to trim on win conditions with Davriel being a source of damage, which means the name 8-Rack would have to change (it's so catchy!). For now, I think it's okay to lean high in win conditions until we figure out the optimal number of them.
I think 8-Rack can afford one more colorless land now that Davriel is bringing up the generic mana pip count up a touch. Hostile Desert is some tech that I noticed from a Magic Online 5-0 list that makes sense. Liliana of the Veil and Raven's Crime put lands into your graveyard quite often, Mutavaults die in combat, and you have a couple of fetchlands in there to fuel Fatal Push revolt anyway.
I've got a maindeck copy of Leyline of the Void up in there, which may look quite rude, but Izzet Phoenix and Dredge are everywhere and neither is a great matchup for a discard strategy. It's fine to cast for four mana, but generally gets discarded to Smallpox or Liliana of Veil later on if you draw it outside of your opening seven.
Smallpox is still sweet, and not necessarily a Turn 2 play. Liliana's Triumph does work in this space to clear out early creatures, so you don't have to worry about Smallpoxing away your second land in some spots. With Davriel, Rogue Shadowmage increasing the three-drop count, you typically want to wait until Turn 4 to fire off Smallpox.
I think Davriel will give 8-Rack quite a shot in the arm in power level, and I can't want to corrupt some minds myself.