docs: added additional comments for #11933

Mage/src/main/java/mage/target/Target.java

@@ -139,6 +139,10 @@ public interface Target extends Serializable {
 
     boolean isRandom();
 
+    /**
+     * WARNING, if you need random choice then call it by target's choose method, not player's choose
+     * see https://github.com/magefree/mage/issues/11933
+     */
     void setRandom(boolean atRandom);
 
     UUID getFirstTarget();

Mage/src/main/java/mage/target/TargetImpl.java

@@ -34,7 +34,7 @@ public abstract class TargetImpl implements Target {
     protected boolean chosen = false;
     // is the target handled as targeted spell/ability (notTarget = true is used for not targeted effects like e.g. sacrifice)
     protected boolean notTarget = false;
-    protected boolean atRandom = false;
+    protected boolean atRandom = false; // for inner choose logic
     protected UUID targetController = null; // if null the ability controller is the targetController
     protected UUID abilityController = null; // only used if target controller != ability controller