Reef Worm 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.

Official card text

When this creature dies, create a 3/3 blue Fish creature token with "When this token dies, create a 6/6 blue Whale creature token with 'When this token dies, create a 9/9 blue Kraken creature token.'"

Complete guide

Reef Worm is a blue creature that embodies the aquatic food chain in a single card. By providing a series of increasingly powerful tokens upon its death, it offers incredible resilience against sweepers and combat trades. It is a favorite for players who enjoy recursive strategies and growing their board presence through sacrifice.

The Lifecycle of the Worm

Reef Worm features a nested triggered ability that triggers when it dies. Initially, it is a simple 0/1, but its death begins a chain reaction. It produces a 3/3 Fish, which later produces a 6/6 Whale, which finally leaves behind a massive 9/9 Kraken. Each stage must die for the next stage to be created, meaning you cannot skip steps without specific external effects.

Step-by-Step Resolution

1. The Reef Worm dies and is put into the graveyard. 2. Its triggered ability is put onto the stack. 3. When the ability resolves, you create a 3/3 blue Fish creature token. 4. This Fish token has its own triggered ability. When the Fish dies, it leaves the battlefield and a new trigger creates a 6/6 blue Whale token. 5. Finally, when the Whale token dies, a third trigger creates a 9/9 blue Kraken token. Each token is a separate permanent and requires a new death event to progress the chain.

Common Mistakes

A common misconception is that the Kraken is created immediately if Reef Worm is exiled. However, these abilities only trigger when the creature 'dies,' which means moving from the battlefield to the graveyard. If Reef Worm or any of its subsequent tokens are exiled or returned to your hand, the chain is broken. Additionally, remember that tokens do technically hit the graveyard before ceasing to exist, which is why their 'dies' triggers still function correctly.

When to Play Reef Worm

Reef Worm is best utilized in decks that can reliably sacrifice their own creatures for value. Since the tokens get progressively larger, you can use the 0/1, 3/3, and 6/6 as fodder for sacrifice outlets, eventually ending up with a 9/9 Kraken for your efforts. It is also excellent protection against 'Destroy all creatures' effects, as you will always be left with a creature after the spell resolves.

Interaction examples

Doubling the Food Chain

Roaming Throne

If you control Roaming Throne and chose 'Worm' as its type, Reef Worm's death triggers twice, giving you two 3/3 Fish tokens. If you chose 'Fish' instead, the death of the 3/3 Fish token would trigger twice, producing two 6/6 Whale tokens. This allows you to branch out the evolution chain into multiple large threats.

Value Sacrifice

Solemn Simulacrum

While Solemn Simulacrum and Reef Worm don't have a direct mechanical synergy, they represent a 'death-value' engine. If both die to a board wipe, you would draw a card from the Simulacrum and create a 3/3 Fish from the Worm, ensuring you have more resources and board presence than your opponents after the dust settles.

The Final Form

Kraken

When you have reached the final stage of the chain, you control a 9/9 Kraken token. Unlike the previous stages, the Kraken token does not have a 'dies' trigger. If the Kraken dies, the chain is officially over, and no more tokens are created from that specific lineage.

Guide written with AI from the official text and rulings. Official English text prevails.