Target selection

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Guide

First decide how the player selects a target, then make the Behavior resolve the same object or collection

An important distinction

Target on the card controls the card-play interaction. The target source in its Behavior controls which objects an Action actually affects. Both must describe the same range. Otherwise, a card may let the player select one target but affect a different object during resolution

Card Target controls player input

Target	Player action	Common target source in Behavior
None	Select no unit	The Behavior decides whether it needs a unit, card, or no target
Single Enemy	Select one living enemy	Opponent reads the enemy submitted by the player
All Enemies	Select no unit	AllEnemies resolves every living enemy
Self	Select no unit	Self resolves the player

tip

Single Enemy displays an aiming arrow and highlights valid units before submission

The card above is still in target selection. The play is submitted only after the player clicks a valid enemy. When the Behavior uses Opponent, it reads that selection

All Enemies skips single-target selection. Its Behavior should use AllEnemies so every living enemy receives the range effect promised by the card text

Meteor Strike above resolves 15 damage on three living enemies at the same time. Its Card Target, Behavior target collection, and player-facing text all describe the same range

Unit Source resolves units from the current 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 Behavior
Opponent	For a player Host, first reads a living non-player Target, then the actual living Attacker in a reaction context, then the first living enemy; for an enemy Host, resolves the player
AllEnemies	Every living enemy, excluding dead units
AllUnits	The living player and all living enemies

Healing, armor, and self-Buffs normally use Self. Single-target attacks use Opponent, while range rules use AllEnemies

A connected port overrides the node field

When a node has both a Target input port and a Source field, the connection has higher priority

Target port connected -> Use the unit or collection supplied by the connection
Target port unconnected -> Resolve the target from the current context through the Source field

tip

This rule lets an Action use Self as its default target and later switch to a dynamic target through a Selector connection. Before switching the port, confirm that the original field no longer controls the result

Card Source reads current card instances

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

These sources read the current piles when a downstream node executes. Evaluating again after moving cards returns the new collection. Save a snapshot first when later logic needs the result from before the move

A Selector chooses targets from a collection

When rules rather than player input decide a target, use a Selector to filter, sort, and limit the collection in order

1. Use Filter to keep units or cards that satisfy the conditions
2. Use Sort to order them by HP, cost, or another value
3. Use Pick, Take, or Random to obtain the objects required by the Action

• Check whether the collection is empty before the Action and use Branch to enter a fallback path

• State the target restriction in the card description

• Give the failure path visible feedback, or reject the invalid action before the card is played

The graph above filters the draw pile to Basic Attack cards, selects one at random, and moves it into the hand. Unit targets use the same structure. For example, sort AllEnemies by HP in ascending order, then take the first element to resolve the living enemy with the lowest HP

Empty results do not become fallback effects automatically

Built-in Actions skip empty, dead, or invalid targets. When the final collection is empty, the Action produces no effect and does not select another object automatically

tip

If an empty result conflicts with the card text or player expectations, handle it explicitly in the Behavior

Opponent, UnitSource, CardSource, and node names belong to Editor configuration and should not appear directly in player-facing card descriptions. Describe the final target instead, such as "Deal 8 damage to the selected enemy" or "Apply 2 Burn to all enemies."