Triggered Abilities

This document provides an overview of triggered abilities in Magic: The Gathering.

What Are Triggered Abilities?

Triggered abilities are abilities that automatically trigger when certain game events occur. They are written as "When/Whenever/At [event], [effect]."

Examples:

  • "When this creature enters the battlefield, draw a card."
  • "Whenever an opponent gains life, you may draw a card."
  • "At the beginning of your upkeep, you gain 1 life."

Triggers

Triggered abilities can trigger based on:

  1. State Changes: "When [state change] occurs..."

    • A creature entering the battlefield
    • A creature dying
    • A creature attacking or blocking

  2. Phase/Step Changes: "At the beginning of [phase]..."

    • At the beginning of upkeep
    • At the beginning of your draw step
    • At the beginning of combat

  3. Player Actions: "Whenever a player [action]..."

    • Whenever a player casts a spell
    • Whenever a player plays a land
    • Whenever a player activates an ability

Resolution Process

When a triggered ability triggers:

  1. The ability is put on the stack the next time a player would receive priority
  2. If multiple abilities trigger at the same time, they go on the stack in APNAP order (Active Player, Non-Active Player)
  3. If multiple abilities trigger for a single player, that player chooses the order
  4. Triggered abilities resolve like any other ability on the stack

Special Types of Triggered Abilities

Delayed Triggered Abilities

These set up an effect that will happen later:

  • "At the beginning of the next end step, return the exiled card to its owner's hand."
  • "At the beginning of your next upkeep, sacrifice this permanent."

State Triggers

These continually check if a condition is true:

  • "When you have no cards in hand, sacrifice this permanent."
  • "When you control no creatures, sacrifice this enchantment."

Implementation Note

For the detailed implementation of triggered abilities in Rummage, including code examples and integration with other systems, see:

These documents provide technical details on how triggered abilities are handled in the game engine.