Game Event Pipeline

The game engine checks for spell effects at many specific steps in the game pipelines. The Game Event Pipeline determines exactly when each active spell contributes its effect.

Events and Spell Effects

Card Text Phrases

A Text Phrase is a Game Event

Containment Hierarchy and Event Bubbling

Event Handling Pipelines

Pipeline for an Event on all Players

Pipeline for an Event on a Spell Target

Events and Spell Effects

Card Text Phrases. Card texts use the following phrases to specify exactly when an effect will happen within a game turn. Each phrase corresponds to one step in a game turn phase or pipeline.

• [player] “at start of turn”
• [player] “after start of turn”
• [player] “before movement”
  • [group] “on exit”
  • [group] “on move”
  • [group] “on enter”
• [player] “after movement”
• [player] “before combat”
  • [group] “start of combat”
    • [group] “start of each combat round”, “every round”
      • [minion] “must attack”
      • [minion] “before checking armor”
      • [minion] “is hit by”, “is hit in combat”
      • [minion] “after checking armor”
        • [minion] “is dying”
        • [minion] “when ... is killed”
        • [minion] “when ... dies”
    • [minion] “when ... hits”, “hits give”
    • [minion] “when ... damages”
    • [minion] “kills an opponent by combat damage”
  • [group] “end of combat”
  • [group] “after combat”
• [player] “after all combat”

A Text Phrase is a Game Event. Internally, every card text phrase is represented as an event, which is a message that can be passed around. When the Sanctum game engine reaches one of the above steps, it broadcasts the event to all active spells in play. Spells work by responding to the events they're interested in, as written on their card texts.

Usually, many different active spells want to respond to the same event. We need a unique order in which to evaluate all active spells. This is handled by event bubbling.

Containment Hierarchy and Event Bubbling. Every spell target defines a “next” spell target for event handling. Whenever a spell target receives an event, it handles the event, and also forwards that event to the “next” spell target in line. Because the “next” targets generally go “upward” toward the globe, this forwarding is called bubbling. Mnemonic: Think of an event as a bubble in a soda, which gradually floats upward. This allows the game engine to provide event-handling inheritance based on dynamic entity containment relationships, which is a useful and intuitive mechanism.

Event Handling Pipelines

Pipeline for an Event on all Players. Most events listed in the phases of a game turn are “untargeted”. They are applied directly to all players.

• For each player in the player initiative sequence
  (initiative, non-initiative, neutral):
  • For each spell in this player's active spell list, from first to last (approximately oldest to youngest):
    • This spell handles (or ignores) this event.
  • Events on a player do not bubble.

Pipeline for an Event on a Spell Target. Most events that occur within the game pipelines are “targeted”, i.e. they pertain to a current spell target.

• For each spell in this spell target's active spell list, from first to last (approximately oldest to youngest):
  • This spell handles (or ignores) this event.
• Bubble this event to the next spell target (and halt when bubbling halts).

We can “unroll” this pipeline to obtain the following more detailed description.

• Anachronism: Even though a group is a spell target, and therefore has its own active spell list, it does not use it, and never has!

v2.20.00 Last updated 2009/03/22