Black is a color full of removal. Most removal spells are around 1-3 mana. There can be removal at higher values up the mana curve, some of these are more impactful than others. Black is also a color that tends to pack more of a punch to your opponent's life total, and is a color that can find you exactly what you are looking for when you need it. All of these can be found in the four-mana slot of a Commander deck and these are the standouts.

Diabolic Tutor

Like I said previously, Black is great at searching out exactly what you need from your deck. Imperial Seal, Vampiric Tutor, and Demonic Tutor are all examples of these cards. They tend to also run a huge price tag if you are considering them for your next build. Diabolic Tutor however, is much more budget. Yes, let's be honest, a four-mana sorcery speed tutor is pretty mediocre, but if you need a card to save yourself or the table, this can get it for you. This itself isn't the most impactful spell, but it can get you a spell that is.

One Ring to Rule Them All

One Ring to Rule Them All is a board wipe on a saga. We have seen this effect in Phyrexian Scriptures, but Phyrexian Scriptures doesn't help kill our opponents like One Ring to Rule Them All does. One Ring to Rule Them All helps fill graveyards. This is helpful for its last chapter ability but could also fit nicely into a Reanimator type strategy.

The second ability is a Slash the Ranks, helping keep the board clear. The last chapter ability drains your opponents for each creature in their graveyard. It helps that you just sent a bunch of creatures to their graveyard to fuel this effect. Try this out in your next Reanimator or Legends-Matter brew or if you are looking at building Master of Keys.

Rankle, Master of Pranks

Rankle, Master of Pranks is my favorite Black four-drop in the game so it had to make an appearance. Impactful cards should cause the game to either shift in your favor or shake up the game for everyone. Rankle accomplishes this by coming down with haste and allowing you to use all of his abilities as long as he connects for damage. Rankle draws you cards, removes creatures, and strips cards out of everyone's hand. All of these effects can be helpful! Rankle is best on turn four, especially at removing creatures, but since he draws you cards, he is impactful at any point of the game. He even is a perfect inclusion into discard centered decks as well!

Biotransference

Artifacts have so much support in Commander. Colorless Commander decks finally have a leg to stand on these days. We even have some support for the artifact archetype thanks to the mono Black Commander deck from Warhammer 40K. Biotransference helps artifact decks in Black by turning all your creatures into artifacts creatures and artifact spells! It also will create a 2/2 creature whenever you cast an artifact spell! This ability is best paired with a Phyrexian Altar or an Ashnod's Altar. Each time you cast an artifact you will get a creature which you can sacrifice to the altars for even more mana! This card is incredibly strong and sometimes forgotten since it's from the Universes Beyond Commander lineup, but don't sleep on it!

Grave Pact

Black is the go-to color for Aristocrat strategies. This is the strategy where you gain benefits for sacrificing your creatures. Grave Pact is one of the key pieces to that strategy as it helps remove threats off the board constantly. This four-mana enchantment can end with the table being completely lopsided in your favor. Grave Pact is one of the most salty cards on this list as players hate to constantly have their creatures removed. If you do plan on playing Grave Pact in your deck, make sure you have ways to finish the game quickly or your opponents may end up just scooping to your constant edict effects.

Crypt Ghast

Crypt Ghast is a great way to jump ahead of your opponents. This four-mana Black creature doubles all of your mana produced from Swamps. It also has the added benefit of having extort as a keyword, which you can use as a mana sink thanks to all the mana you are gaining. Black is full of large Demon type creatures that are incredibly powerful, however, their mana cost is extremely high. Crypt Ghast helps you reach these higher cost cards faster as well as helping to drain your opponent's life total while also boosting your own. Crypt Ghast was a very good contender to be the best 4 mana Black spell, however, there is a creature that can help us win the game even faster for the same mana cost.

Bloodletter of Aclazotz

Bloodletter of Aclazotz is a four-mana flying Vampire Demon that reads, "If an opponent would lose life during your turn, they lose twice that much life instead." I believe this is the best four-mana card you could possibly cast in Black. This card essentially halfs your opponent's life totals since you only need to deal half the amount you would normally need to deal to kill the entire table. This card works so well with cards like Blood Artist and Zulaport Cutthroat that ping the whole table slowly. Bloodletter is also a Vampire and a Demon which are the strongest creature types that Black has to offer, so it fits in any typal deck of those respective types. Wound Reflection is a six-mana enchantment for a reason. Bloodletter is a card that will continue to be a powerhouse in Commander as we know it for the foreseeable future!

Black is a very powerful color in all aspects of Magic, especially Commander. I hope this list helps you pack a punch in that 4 mana slot of your next or even current brew!

See you on the battlefield!

-Nigel