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Professor Onyx

Legendary Planeswalker — Liliana

Magecraft — Whenever you cast or copy an instant or sorcery spell, each opponent loses 2 life and you gain 2 life.
+1: You lose 1 life. Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
−3: Each opponent sacrifices a creature with the greatest power among creatures that player controls.
−8: Each opponent may discard a card. If they don't, they lose 3 life. Repeat this process six more times.

CMC
6
Mana cost
{4}{B}{B}
Color identity
B
Rarity
mythic
Set
Strixhaven: School of Mages
Price
$10.48
EDHREC rank
#2369
Buy on TCGplayer
Professor Onyx card art
Professor Onyx drains the table for every spell cast while generating loyalty and threatening an ultimate that refills your hand — six mana buys a continuous life-swing engine, not a one-shot effect. The Chain of Smog combo, where repeated discard-and-copy triggers drain opponents to zero, is the reason Toshiro Umezawa decks run her at a 71% clip.

Best Commanders

Commanders with the highest synergy

01
Toshiro Umezawa

Toshiro Umezawa

70.7% of decks · synergy 0.65

Toshiro Umezawa's ability to flash back instant spells from the graveyard pairs directly with Professor Onyx's magecraft trigger, turning every recurred removal spell into a free drain — the two form a passive damage engine that scales with the removal suite.

02
Winter, Cynical Opportunist

Winter, Cynical Opportunist

54.6% of decks · synergy 0.52

Winter, Cynical Opportunist rewards casting spells on opponents' turns, and Professor Onyx converts each of those instants into a drain-and-gain pulse, letting the deck accrue life and pressure opponents passively while Winter's discard effects keep the table off-balance.

03

Liliana, Heretical Healer

43.2% of decks · synergy 0.37

Liliana, Heretical Healer decks are already stacking Liliana planeswalkers, and Professor Onyx slots in as both a standalone threat and a second magecraft source — her drain triggers tick up with every spell in a deck built to run plenty of them.

04
Gwenom, Remorseless

Gwenom, Remorseless

38.5% of decks · synergy 0.33

Gwenom, Remorseless incentivizes black spell-slinging and life loss, and Professor Onyx stacks perfectly: every cast drains opponents, feeding Gwenom's payoffs while the planeswalker builds toward a game-ending ultimate.

05
Carth the Lion

Carth the Lion

29.5% of decks · synergy 0.27

Carth the Lion fetches planeswalkers and pumps their loyalty counters, which means Professor Onyx enters with more loyalty and reaches her hand-refilling ultimate faster — Carth makes the six-mana ask feel considerably cheaper.

Format Analysis

Where it lives, where it can’t

FormatVerdict
commander legal
legacy legal
modern legal
pioneer legal
standard not legal
vintage legal
pauper not legal
oathbreaker legal

Commander is where Professor Onyx does her best work: magecraft hits all opponents simultaneously, so each spell drains three players at once and the life totals shift faster than a 1v1 format ever allows. In Pioneer and Modern, she's legal but rarely seen — six mana is a steep ask in those formats, and planeswalkers at that cost face a higher bar when they're only pressuring one opponent. Legacy and Vintage can support the mana, but those formats resolve games before a six-drop planeswalker gets to activate twice. Oathbreaker is worth flagging: Professor Onyx is a legal planeswalker commander there, and the Chain of Smog line is a known kill in that 20-life format.

Key Combos

Combo lines featuring this card

Budget Alternatives

Cheaper options that do most of the same work

Torbran, Thane of Red Fell is a different color and a different angle, so the honest swap within black is Ob Nixilis, the Adversary or a drain-on-a-stick like Exquisite Blood paired with a cheaper life-loss engine — neither replicates the magecraft engine, but they close games in the same life-drain lane. If the Chain of Smog combo is the draw, the combo itself is cheap; the professor is the expensive half, and there's no direct substitute for the magecraft trigger at a lower price point.

Price Context

Current price

$10.48 mid tier

At $10.48, Professor Onyx sits in the mid tier — expensive enough to feel like a deliberate inclusion, cheap enough that the Chain of Smog combo package doesn't require a major budget commitment. The price is stable for a card with a known infinite combo attached; it won't spike, but it won't crater either.

Explore

Sources

Mentioned

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Updated . Data from Scryfall, EDHREC, and Commander Spellbook.