diff --git a/Mage/src/main/java/mage/abilities/effects/common/ruleModifying/CombatDamageByToughnessTargetEffect.java b/Mage/src/main/java/mage/abilities/effects/common/ruleModifying/CombatDamageByToughnessTargetEffect.java
index 7d7bc8de8cb..36da6ea92d2 100644
--- a/Mage/src/main/java/mage/abilities/effects/common/ruleModifying/CombatDamageByToughnessTargetEffect.java
+++ b/Mage/src/main/java/mage/abilities/effects/common/ruleModifying/CombatDamageByToughnessTargetEffect.java
@@ -35,7 +35,7 @@ public class CombatDamageByToughnessTargetEffect extends ContinuousEffectImpl {
     public boolean apply(Game game, Ability source) {
         Set<Permanent> set = targetPointer.getTargets(game, source).stream()
             .map(game::getPermanent)
-            .filter(Objects::isNull)
+            .filter(Objects::nonNull)
             .collect(Collectors.toSet());
 
         FilterCreaturePermanent filter = new FilterCreaturePermanent();
diff --git a/Mage/src/main/java/mage/abilities/keyword/BackupAbility.java b/Mage/src/main/java/mage/abilities/keyword/BackupAbility.java
index 3a22b6e58a2..d88691e9247 100644
--- a/Mage/src/main/java/mage/abilities/keyword/BackupAbility.java
+++ b/Mage/src/main/java/mage/abilities/keyword/BackupAbility.java
@@ -18,6 +18,25 @@ import java.util.ArrayList;
 import java.util.List;
 
 /**
+ * 702.165. Backup
+ * <p>
+ * 702.165a Backup is a triggered ability. “Backup N” means “When this creature enters the battlefield,
+ * put N +1/+1 counters on target creature. If that’s another creature, it also gains the non-backup
+ * abilities of this creature printed below this one until end of turn.” Cards with backup have one or more
+ * abilities printed after the backup ability. (Some cards with backup also have abilities printed before
+ * the backup ability.)
+ * <p>
+ * 702.165b If a permanent enters the battlefield as a copy of a permanent with a backup ability or a token
+ * is created that is a copy of that permanent, the order of abilities printed on it is maintained.
+ * <p>
+ * 702.165c Only abilities printed on the object with backup are granted by its backup ability. Any abilities
+ * gained by a permanent, whether due to a copy effect, an effect that grants an ability to a permanent, or an
+ * effect that creates a token with certain abilities, are not granted by a backup ability.
+ * <p>
+ * 702.165d The abilities that a backup ability grants are determined as the ability is put on the stack.
+ * They won’t change if the permanent with backup loses any abilities after the ability is put on the stack
+ * but before it resolves.
+ *
  * @author TheElk801
  */
 public class BackupAbility extends EntersBattlefieldTriggeredAbility {
@@ -65,13 +84,23 @@ public class BackupAbility extends EntersBattlefieldTriggeredAbility {
         addAbility(ability, null, dontAddToCard);
     }
 
+    /**
+     *
+     * @param ability
+     * @param watcher
+     * @param dontAddToCard use it on multiple instances of backups (example: Conclave Sledge-Captain)
+     */
     public void addAbility(Ability ability, Watcher watcher, boolean dontAddToCard) {
         if (watcher != null) {
             ability.addWatcher(watcher);
         }
+
+        // parent card must have only 1 instance of ability
         if (!dontAddToCard) {
             card.addAbility(ability);
         }
+
+        // target permanent can have multiple instances of ability
         abilitiesToAdd.add(ability);
         CardUtil.castStream(this.getEffects().stream(), BackupEffect.class)
                 .forEach(backupEffect -> backupEffect.addAbility(ability));