Introduce new batch event for life lost for a specific player (#13071)

* Introduce new batch event for life lost for a specific player

closes #12202, fix #10805

* implement [DSC] Valgavoth, Harrower of Souls

* text fixes

Mage/src/main/java/mage/abilities/dynamicvalue/common/SavedLifeLossValue.java

@@ -0,0 +1,49 @@
+package mage.abilities.dynamicvalue.common;
+
+import mage.abilities.Ability;
+import mage.abilities.dynamicvalue.DynamicValue;
+import mage.abilities.effects.Effect;
+import mage.game.Game;
+
+/**
+ * @author Susucr
+ */
+public enum SavedLifeLossValue implements DynamicValue {
+    MANY("many"),
+    MUCH("much");
+
+    private final String message;
+
+    private static final String key = "SavedLifeLoss";
+
+    /**
+     * value key used to store the amount of life lost
+     */
+    public static String getValueKey() {
+        return key;
+    }
+
+    SavedLifeLossValue(String message) {
+        this.message = "that " + message;
+    }
+
+    @Override
+    public int calculate(Game game, Ability sourceAbility, Effect effect) {
+        return (Integer) effect.getValue(getValueKey());
+    }
+
+    @Override
+    public SavedLifeLossValue copy() {
+        return this;
+    }
+
+    @Override
+    public String toString() {
+        return message;
+    }
+
+    @Override
+    public String getMessage() {
+        return "";
+    }
+}