[DRC] Implement Prophet of the Scarab

Also adds a DynamicValue that finds the largest of multiple DynamicValues.

Mage/src/main/java/mage/abilities/dynamicvalue/MaximumDynamicValue.java

@@ -0,0 +1,49 @@
+package mage.abilities.dynamicvalue;
+
+import mage.abilities.Ability;
+import mage.abilities.effects.Effect;
+import mage.game.Game;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class MaximumDynamicValue implements DynamicValue {
+
+    private final List<DynamicValue> dynamicValues;
+
+    /**
+     * Creates a {@link DynamicValue} that finds the maximum of multiple
+     * {@link DynamicValue}s.
+     *
+     * @param dynamicValues The dynamic values to add together.
+     */
+    public MaximumDynamicValue(DynamicValue... dynamicValues) {
+        this.dynamicValues = Arrays.asList(dynamicValues);
+    }
+
+    /**
+     * Creates a {@link DynamicValue} that finds the maximum of multiple
+     * {@link DynamicValue}s.
+     *
+     * @param dynamicValues The dynamic values to add together.
+     */
+    public MaximumDynamicValue(List<DynamicValue> dynamicValues) {
+        this.dynamicValues = dynamicValues;
+    }
+
+    @Override
+    public int calculate(Game game, Ability sourceAbility, Effect effect) {
+        return dynamicValues.stream().mapToInt(d -> d.calculate(game, sourceAbility, effect)).max().orElse(0);
+    }
+
+    @Override
+    public MaximumDynamicValue copy() {
+        return new MaximumDynamicValue(this.dynamicValues);
+    }
+
+    @Override
+    public String getMessage() {
+        return this.dynamicValues.stream().map(DynamicValue::getMessage).collect(Collectors.joining(" "));
+    }
+}