Windcrag Siege — Tarkir: Dragonstorm Promos #235p

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.