Add Cover card and implement block

Assets/Battle/BattleParticipant.cs

@@ -1,4 +1,5 @@
-using System.Collections;
+using System;
+using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
@@ -7,6 +8,7 @@ public class BattleParticipant
     protected string displayName;
     protected int hp;
     protected int maxHP;
+    protected int block;
 
     public void Init() {
         this.hp = this.maxHP;
@@ -25,7 +27,24 @@ public class BattleParticipant
     }
 
     public void DealDamage(int damage) {
+        int blockedDamage = Math.Min(damage, this.block);
+        if (blockedDamage > 0) {
+            this.block -= blockedDamage;
+            damage -= blockedDamage;
+        }
         this.hp -= damage;
         if (this.hp < 0) this.hp = 0;
     }
+
+    public void AddBlock(int block) {
+        this.block += block;
+    }
+
+    public void ResetBlock() {
+        this.block = 0;
+    }
+
+    public int GetBlock() {
+        return this.block;
+    }
 }