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docs/Card-scripting-API/Replacements.md

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+Replacement create replacement effects, as you'd expect. Their script
+follows the format introduced by AbilityFactory; simply begin a line
+with "R:", to indicate that it's for a replacement effect, followed by a
+collection of name-value pairs (name and value are separated by $)
+separated by pipes (|). All Replacement effects expect an "Event$"
+parameter, which declares what event should be replaced. Most replacement effects will also have a "ReplaceWith$" parameter which points to an SVar which contains what should replace the event. They may have a "Prevent$True" parameter, instead though, which means that nothing happens instead of the event.
+
+Similarly to triggers, the replacing code can access special variables
+pertaining to the event it replaced (like triggered-variables). These
+are specific to each event, and is listed below. Most replacement effects
+will also have a "Description$" parameter which is simply the card text
+for the ability.
+
+## DamageDone
+
+DamageDone events are checked when damage is about to be assigned to a
+card or player. There are 5 special parameters:
+
+  - ValidSource - The damage source must match this for the event to be
+    replaced.
+  - ValidTarget - The damage target must match this for the event to be
+    replaced.
+  - DamageAmount - The amount of damage must match this.
+  - IsCombat - If true, the damage must be combat damage, if false, it
+    can't be.
+  - IsEquipping - If true, the host card must be equipping something.
+
+There are 3 Replaced-variables:
+
+  - DamageAmount - The amount of damage to be assigned.
+  - Target - The target of the damage.
+  - Source - The source of the damage.
+
+## Discard
+
+Discard events are checked when a player is about to discard a card.
+There are 4 special parameters:
+
+  - ValidPlayer - The player who would discard must match this.
+  - ValidCard - The the card that would be discarded must match this.
+  - ValidSource - The card causing the discard must match this.
+  - DiscardFromEffect - If true, only discards caused by spells/effects
+    will be replaced. Cleanup/statebased discards will not.
+
+There are 2 Replaced-variables:
+
+  - Card - The card that would be discarded.
+  - Player - The player that would have discarded
+
+## Draw
+
+Draw events are checked when a player is about to draw a card. There is
+1 special parameter:
+
+  - ValidPlayer - The player who would draw must match this.
+
+There are no Replaced-variables.
+
+## GainLife
+
+GainLife events are checked when a player would gain life. There is 1
+special parameter:
+
+  - ValidPlayer - The player who would gain life must match this.
+
+There is 1 Replaced-variable:
+
+  - LifeGained - The amount of damage to be gained.
+
+## GameLoss
+
+GameLoss events are checked when a player would lose. There is 1 special
+parameter:
+
+  - ValidPlayer - The player who would lose must match this.
+
+There are no Replaced-variables.
+
+## Moved
+
+Moved events are checked when a card would be moved between zones. There
+are 3 special parameters:
+
+  - ValidCard - The moving card must match this.
+  - Origin - The card must be moving from this zone.
+  - Destination - The card must be moving to this zone.
+
+There is 1 Replaced-variable:
+
+  - Card - The moving card.