Target Selection

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Guide

Keep card text, player input, and FlowGraph target resolution aligned so every rule affects only its intended objects

Card Target defines player input

Editor Label	Runtime Enum	Player action	Expected source in Behavior
None	CardTargetMode.None	Select no unit	The Graph decides whether it needs a unit, card, or no target
Single Enemy	CardTargetMode.SingleEnemyUnit	Select one living enemy	Opponent reads the submitted enemy from Card Context
All Enemies	CardTargetMode.AllEnemyUnits	Select no unit	AllEnemies resolves every living enemy
Self	CardTargetMode.Self	Select no unit	Self resolves the player

Single Enemy: Before the UI submits the selection, the card shows the pending target with an aiming arrow and unit highlight.

All Enemies: The card skips this selection. Its Behavior must resolve AllEnemies so every living enemy receives the range effect promised by the text. Meteor Strike therefore displays the same damage on all three enemies.

UnitSource resolves units from context

Source	Resolved result
Self	The current Host: the player in a player Card, the owner in a Status, or the acting enemy in an Enemy Graph
Opponent	For a Player Host, the submitted living enemy, falling back to the first living enemy when none was submitted. For an Enemy Host, the player
AllEnemies	Every living enemy, excluding dead units
AllUnits	The living player and all living enemies

Use Self for healing, armor, and self-Buffs, Opponent for a single-target card effect on the selected enemy, and AllEnemies for area rules.

A connected Target Port overrides the Source Field

When a node has both a target input pin, or Target Port, and a static target field, or Source Field, the connection takes priority.

• Connected pin: The node uses the value or reference supplied by the connection. The TargetSource dropdown in the static panel is ignored automatically.
• Unconnected pin: The node falls back to the default contextual target selected in TargetSource, such as Self or Active Unit.

CardSource and live card-instance resolution

CardSource resolves matching card-instance collections at runtime. Whenever a downstream node executes, these Sources read the latest state from the current battle.

Source	Resolved result
ThisCard	The CardInstance currently resolving
HandPile	The current hand
DrawPile	The current draw pile
DiscardPile	The current discard pile
ExhaustPile	The current exhaust pile
AllPiles	The combined hand, draw pile, discard pile, and exhaust pile

Filtering Selector collections

Use a Selector when game logic, rather than manual player input, decides the target of a card effect. Connections can filter, sort, and limit an initial collection until only the exact target objects remain.

• Filter: Retains objects that meet specific conditions, such as damage cards or enemies carrying Poison.
• Sort: Orders the retained objects, such as highest to lowest cost or lowest to highest HP.
• Pick / Take / Random: Extracts the exact objects needed by the next Action, such as 1 random card or the first 2 elements.

The graph below filters the draw pile to all Basic Attack cards, selects one at random, then moves it into the hand.

Unit selection follows the same logic. To resolve the enemy with the lowest HP, connect All Enemies to a Filter that retains living units, connect that to a Sort ordered by ascending HP, then use Pick Element to extract the first element and pass it to the damage node.

Fault tolerance and design rules for empty results

Runtime fault tolerance through silent execution

Built-in FlowGraph Actions protect against empty values.

• When an Action resolves its targets, it skips missing, dead, or invalid objects automatically.
• If the final target collection is empty, such as when damage targets all enemies after every enemy has died, the Action does not throw an error or stop the rest of the Graph. It skips safely and continues.

Do not rely on silent skipping to communicate a rule

The code may remain error-free, but if nothing happening would violate player expectations, do not leave the result to silent skipping. Follow these design rules:

1. Intercept with a Branch: Use a Condition and Branch to test whether the target is empty. When it is, follow another path with a visible fallback effect or message.
2. Make the text explicit: State the restriction in the card description so the player is not misled.
3. Localize player-facing text correctly:
   • Player-facing text in the description field: Use direct, readable in-game language, such as "Deal 8 damage to the selected enemy" or "Apply 2 Burn to all enemies."
   • Never expose implementation fields: Terms such as Opponent, UnitSource, CardSource, and Collection Operator exist only for Editor graph construction and must never appear in player-facing card descriptions or UI.