a.cs

public class BattleMain: MonoBehaviour {
  public event EventHandler<List<UnitInfo>> UnitInfoUpdateHandler;
  
  public SomeBattleProcess() {
    // ~~~~何らかの戦闘処理でUnitInfoのリストが更新
    UnitInfoUpdateHandler(this, this.unitInfoList);
  }
}

////////////////////////////////

public class MapViewManager: MonoBehaviour {
  [SerializeField]
  BattleMain main;

  void Start() {
    main.UnitInfoUpdateHandler += this.OnUnitListUpdated;
  }
  
  void OnUnitListUpdated(object sender, List<UnitInfo> unitInfoList) {
    // Viewの更新処理
  }
}