Wormfang Turtle 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 enters, exile a land you control. When this creature leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Complete guide

Wormfang Turtle is a unique blue creature that temporarily devours your territory to fuel its presence on the battlefield. As a Nightmare Turtle Beast, it forces a tactical sacrifice of your resources that can be reclaimed once it departs. Mastering this card requires understanding how to manage your mana base while leveraging its defensive stats.

What It Does

Wormfang Turtle features two linked triggered abilities that manage a specific land card. The first ability is an 'enters-the-battlefield' trigger that requires you to exile a land you control. The second is a 'leaves-the-battlefield' trigger that ensures the return of that specific land once the Turtle is no longer in play. Because these are separate triggers, the land is not gone forever, but it will be unavailable for mana production while the Turtle remains.

Resolution Step-by-Step

When Wormfang Turtle enters the battlefield, its first ability goes on the stack. Upon resolution, you choose one land you control and exile it. The land remains in the exile zone as long as the Turtle is on the battlefield. When the Turtle leaves the battlefield for any reason—whether it is destroyed, exiled, or returned to your hand—its second ability triggers. This ability returns the previously exiled land card to the battlefield under its owner's control, untapped unless specified otherwise by the land's own text.

Common Mistakes

A frequent error is forgetting that the land is returned under its owner's control, which is important if you exiled a land you previously gained control of from an opponent. Additionally, players often forget that the land returns as a new object; any enchantments like Auras or counters that were on the land before it was exiled will not stay on it when it returns to the battlefield. Finally, if Wormfang Turtle leaves the battlefield before its first ability resolves, the 'leaves' ability will trigger and do nothing, and then the 'enters' ability will resolve, exiling the land permanently.

When to Play It

Wormfang Turtle is most effective in decks that can capitalize on 'enters-the-battlefield' triggers of lands. Since the land returns to play when the Turtle leaves, you can trigger abilities like Landfall twice for a single land card. It is also a solid defensive unit for its mana cost, provided you have a spare land that you do not need for immediate mana production.

Interaction examples

Basic Deployment

You cast Wormfang Turtle for three mana. When it enters the battlefield, you choose a Basic Island you control and exile it. You now have a 2/4 creature but one less mana source available. If your opponent casts a spell to destroy the Turtle, the Island immediately returns to the battlefield under your control.

Re-triggering Land Effects

You have a land with a special ability that triggers when it enters the battlefield. By playing Wormfang Turtle and exiling that land, you set up a situation where you will get that entry effect again later. When the Turtle eventually leaves the battlefield, the land returns, and its 'enters-the-battlefield' ability triggers a second time.

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