Tannuk, Steadfast Second 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

Other creatures you control have haste. Artifact cards and red creature cards in your hand have warp . (You may cast a card from your hand for its warp cost. Exile that permanent at the beginning of the next end step, then you may cast it from exile on a later turn.)

Complete guide

Tannuk, Steadfast Second is a powerful Kavu Pilot that grants your board immediate speed and introduces a unique way to cheat out permanents. By utilizing the warp ability, you can deploy threats early to gain tactical advantages before they return for a second appearance later in the game.

Haste and Hand Manipulation

Tannuk provides a static ability that gives other creatures you control haste, allowing them to attack or use tap abilities the turn they enter the battlefield. Additionally, Tannuk grants a warp cost to all artifact cards and red creature cards in your hand. This alternative casting cost allows you to play high-value cards for just three mana, though they won't stay on the battlefield for long.

The Warp Cycle Explained

When you cast a card for its warp cost, it enters the battlefield normally, triggering any 'enters' effects. At the beginning of the next end step, a delayed triggered ability forces you to exile that permanent. Crucially, the warp keyword includes a special permission: you may cast that card from exile on a later turn by paying its normal mana cost, effectively giving you two uses of the same card.

Strategic Timing and Common Pitfalls

It is important to remember that if the warped permanent leaves the battlefield before the end step (for example, if it is destroyed or bounced), the delayed trigger to exile it will fail to find it, and you won't be able to cast it from exile later. Also, note that Tannuk must be on the battlefield for the cards in your hand to have the warp ability; if Tannuk leaves play, the cards in your hand revert to their normal casting costs.

Interaction examples

Double Value with Solemn Simulacrum

Solemn Simulacrum

With Tannuk on the battlefield, you cast Solemn Simulacrum for its warp cost of {2}{R}. It enters, and you search for a basic land. Because of Tannuk, the Simulacrum has haste and can attack immediately. At the end step, it is exiled. On a subsequent turn, you can cast it again from exile for its normal {4} cost to search for a second land.

Strategic Selection with Roaming Throne

Roaming Throne

You use Tannuk's ability to warp in Roaming Throne for {2}{R}. As it enters, you choose 'Kavu'. The Throne now has haste and Ward {2}. If you activate an ability of another Kavu, it will trigger an additional time. At the beginning of the end step, the Throne is exiled, but you retain the option to cast it from exile later to permanently double your Kavu triggers.

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