Windcrag Siege 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

As this enchantment enters, choose Mardu or Jeskai. • Mardu — If a creature attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time. • Jeskai — At the beginning of your upkeep, create a 1/1 red Goblin creature token. It gains lifelink and haste until end of turn.

Complete guide

Windcrag Siege is a versatile enchantment that allows you to choose between two powerful combat-oriented strategies as it enters the battlefield. Whether you want to double your attacking triggers or build a steady army of tokens, this card provides consistent value for Mardu and Jeskai colors. Choosing the right mode at the right time is key to maximizing your board state.

Choosing Your Path

As Windcrag Siege enters the battlefield, you must choose either Mardu or Jeskai. This choice happens before the permanent is actually on the battlefield, so it cannot be responded to. If you choose Mardu, you gain a static effect that doubles 'when a creature attacks' triggered abilities. If you choose Jeskai, you gain a triggered ability that occurs at the start of every one of your upkeep steps.

The Mardu Advantage

The Mardu mode specifically looks for abilities that trigger because a creature is attacking. This includes abilities that start with 'Whenever this creature attacks' or 'Whenever a creature you control attacks.' It is important to note that this does not double abilities that trigger when a creature is blocked or when it deals combat damage, as those events are distinct from the act of attacking.

The Jeskai Legion

When Jeskai is chosen, you create a 1/1 red Goblin creature token during each of your upkeeps. This token is unique because it gains both lifelink and haste until the end of that specific turn. Because it has haste, you can use it to attack immediately during your combat phase or tap it for abilities that require the tap symbol, such as those found on other permanents you might control.

Timing and Strategy

Select Mardu when you already have a board full of creatures with powerful attack triggers to overwhelm your opponent with value. Conversely, select Jeskai if you are low on creatures or need to establish a defense; the lifelink on the produced Goblin can help stabilize your life total during an aggressive match.

Interaction examples

Generating the Horde

Goblin

If you choose Jeskai as Windcrag Siege enters, your upkeep begins and the trigger goes on the stack. Once it resolves, you create a 1/1 red Goblin token. For the duration of this turn, that specific token has lifelink and haste. This allows you to attack with it immediately to gain life, even though it was just created.

Static Tax vs. Attack Triggers

Ghostly Prison

Note that Mardu only doubles your own triggered abilities. If an opponent controls Ghostly Prison, its effect is a static requirement to pay mana, not a triggered ability. Therefore, Windcrag Siege does not interact with the 'tax' your opponent imposes on your attackers. However, if you have an ability that triggers when you pay that cost or when your creature successfully attacks, that ability would trigger twice.

Triggered Ability Types

Smothering Tithe

If you choose Mardu, Windcrag Siege only doubles abilities triggered by creatures attacking. Smothering Tithe triggers when an opponent draws a card. Since drawing a card is not the same as a creature attacking, Smothering Tithe will still only trigger once per card drawn, even with Windcrag Siege on the battlefield.

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