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Maester SeymourHow it works & interactions with other cards

By the ManaCount desk· 3 min read· Final Fantasy Commander· June 13, 2025
Carte Magic Maester Seymour

Maester Seymour is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

01

Official card text

At the beginning of combat on your turn, put a number of +1/+1 counters equal to Maester Seymour's power on another target creature you control. {3}{G}{G}: Monstrosity X, where X is the number of counters among creatures you control. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)

How it works : Maester Seymour

Original English text — Wizards of the Coast / Scryfall

  1. #1· Wizards of the Coast

    The value of X is determined only once, as Maester Seymour's last ability resolves.

    No other card is named in this ruling.

  2. #2· Wizards of the Coast

    Monstrous isn't an ability that a creature has. It's just something true about that creature. If the creature stops being a creature or loses its abilities, it will continue to be monstrous.

    No other card is named in this ruling.

  3. #3· Wizards of the Coast

    If Maester Seymour is no longer on the battlefield when its first ability resolves, use its power as it last existed on the battlefield to determine how many +1/+1 counters to put on the target creature.

    No other card is named in this ruling.

  4. #4· Wizards of the Coast

    Once a creature becomes monstrous, it can't become monstrous again. If the creature is already monstrous when the monstrosity ability resolves, nothing happens.

    No other card is named in this ruling.

02

Popular combos

Real combos played by the community, sorted by popularity.

Maester Seymour
+Sage of Hours
#1

Maester Seymour + Sage of Hours

Infinite turnsLock
  1. 1At the beginning of your combat phase, Maester Seymour triggers, putting at least five +1/+1 counters on Sage of Hours.
  2. 2Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
  3. 3Repeat each turn.
Maester Seymour
+Crystalline Crawler
+Aggravated Assault
#2

Maester Seymour + Crystalline Crawler + Aggravated Assault

Infinite colored manaInfinite combat phasesInfinite untap of creatures you controlInfinite mana creatures you control can produce
  1. 1At the beginning of your combat phase, Maester Seymour triggers, putting at least five +1/+1 counters on Crystalline Crawler.
  2. 2Move to your postcombat main phase.
  3. 3Activate Crystalline Crawler's first ability five times by removing five +1/+1 counters from it, adding {3}{R}{R}.
  4. 4Activate Aggravated Assault by paying {3}{R}{R}, untapping all creatures you control and causing you to get an additional combat and main phase after this one.
  5. 5Repeat.
Maester Seymour
+Crystalline Crawler
+Hellkite Charger
#3

Maester Seymour + Crystalline Crawler + Hellkite Charger

Infinite colored manaInfinite combat phasesInfinite +1/+1 counters on creatures you control
  1. 1At the beginning of your combat phase, Maester Seymour triggers, putting at least seven +1/+1 counters on Crystalline Crawler.
  2. 2Declare Hellkite Charger as an attacker, triggering its ability.
  3. 3Holding priority, activate Crystalline Crawler's first ability seven times by removing seven +1/+1 counters from it, adding {5}{R}{R}.
  4. 4Resolve the Hellkite Charger trigger, causing you to pay {5}{R}{R} to untap all attacking creatures you control and to get an additional combat phase after this one.
  5. 5Repeat.
Maester Seymour
+Crystalline Crawler
+Najeela, the Blade-Blossom
#4

Maester Seymour + Crystalline Crawler + Najeela, the Blade-Blossom

Infinite creature tokens with hasteInfinite colored manaInfinite combat phasesInfinite +1/+1 counters on creatures you control
  1. 1At the beginning of your combat phase, Maester Seymour triggers, putting at least five +1/+1 counters on Crystalline Crawler.
  2. 2Activate Crystalline Crawler's first ability five times by removing five +1/+1 counters from it, adding {W}{U}{B}{R}{G}.
  3. 3Activate Najeela by paying {W}{U}{B}{R}{G}, untapping all attacking creatures you control and causing you to get an additional combat phase after this one.
  4. 4Repeat.
03

Legal formats

legacyvintagecommanderoathbreakerdueltlr
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