How to Pilot Professor Onyx in Magic: The Gathering Arena Brawl

To pilot Professor Onyx successfully in Magic: The Gathering Arena Brawl, play as a mono-black control deck that clears the board in turns 1 through 5, casts Professor Onyx on turn 6, and closes the game by chaining cheap removal and Learn spells to trigger Magecraft. Because she costs six mana (4BB), casting her onto a contested board without immediate protection leaves her vulnerable to combat damage and costly commander tax.

Planeswalker Mechanics and Priority Abilities

Professor Onyx enters the battlefield with five loyalty counters. Her passive ability and three loyalty abilities dictate how you sequence your turns:

Static Magecraft Ability: Whenever you cast or copy an instant or sorcery spell, each opponent loses 2 life and you gain 2 life. This creates a four-point life swing with every spell, offsetting early damage and converting removal into direct player damage.
-3 Loyalty Ability: Forces an opponent to sacrifice the creature with the greatest power among creatures they control. Activate this immediately upon resolution if an opponent controls a single large threat. Because it is an edict effect, it removes creatures protected by hexproof, ward, or indestructible.
+1 Loyalty Ability: Lets you look at the top three cards of your library, put one into your hand, and put the rest into your graveyard at the cost of 1 life. Use this when the board is clear to dig for lands, sweepers, or cheap spells.
-8 Loyalty Ability: Forces an opponent to discard a card or lose 3 life seven consecutive times. Activate this as a lethal finisher when your opponent's hand is low or their life total is under 21.

The Learn and Lesson Sideboard Package

In Magic: The Gathering Arena Brawl, the Learn mechanic lets you fetch cards from a dedicated seven-card Lesson sideboard. In a Professor Onyx deck, each Learn spell represents two separate Magecraft triggers: one from casting the initial spell, and a second when you cast the retrieved Lesson.

Cards like Eyetwitch and Hunt for Specimens provide cheap early bodies that block aggressively and fetch situational answers without depleting cards from your main deck.

Lesson Card	Mana Cost	Primary Tactical Function	Optimal Timing
Environmental Sciences	2 Generic	Fetches basic land; gains 2 life	Turns 2–4 to guarantee land drops
Introduction to Prophecy	3 Generic	Scries 2 and draws 1 card	Mid-game card selection
Necrotic Fumes	1BB	Exiles target creature via creature sacrifice	Mid-to-late game spot removal
Introduction to Annihilation	5 Generic	Exiles any nonland permanent	Removing artifacts or enchantments
Mascot Exhibition	7 Generic	Summons 2/1, 3/2, and 4/4 creature tokens	Late-game board presence

Early-Game Turn Progression

Do not rush to deploy your commander early. Spend the opening five turns establishing board control:

Turns 1–2: Disrupt your opponent's curve with targeted discard like Thoughtseize and Duress, or kill low-cost threats using Cut Down and Fatal Push. Deploy Eyetwitch or cast Hunt for Specimens to acquire early Lessons.
Turns 3–4: Thin opposing boards with edicts such as Sheoldred's Edict and Liliana's Triumph. If your opponent develops a wide board of small creatures, reset the game state with sweepers like The Meathook Massacre, Ritual of Soot, or Toxic Deluge.
Turn 5: Play hand disruption to strip counterspells or removal from the opponent's hand in preparation for casting your commander next turn.
Turn 6 and Later: Resolve Professor Onyx. Use her -3 ability to eliminate the opponent's strongest threat, or use her +1 ability if the board is empty.

Magecraft Chaining and Win Conditions

Once Professor Onyx is established on the board, prioritize casting multiple low-mana spells in a single turn rather than one expensive spell.

A standard execution loop uses Hunt for Specimens (two mana) to trigger Magecraft for 2 drain while creating a 1/1 Pest token. The Learn trigger retrieves Necrotic Fumes from your sideboard. Sacrificing the Pest token to cast Necrotic Fumes (three mana) triggers Magecraft a second time, draining another 2 life while exiling an opposing creature. This five-mana sequence drains 4 life, restores 4 life, eliminates an enemy creature, and keeps Professor Onyx protected. Repeat cheap spell sequences until the opponent's life total reaches zero or you activate her -8 ultimate.

Matchup Strategies and Strategic Limitations

Midrange and Voltron: Professor Onyx strongly counters decks relying on a single heavily buffed or protected commander. Use her -3 ability to bypass protection keywords and remove the commander directly.
Counterspell Control: Recasting Professor Onyx after removal or counterspells incurs a severe commander tax (eight mana for the second cast). Do not cast her into open blue mana; lead with Duress or Thoughtseize to bait or eliminate counterspells first.
Go-Wide Aggressive Decks: Because her -3 ability removes only one creature, it is ineffective against wide token swarms. Hold mass board sweepers in hand and clear the board completely before deploying Professor Onyx.