public void AddBlockInstance(CardInstance cardAttacker, CardInstance cardBlocker,
                                     ref int count)
        {
            var blockInstance = GetBlockInstanceOfAttacker(cardAttacker);

            if (blockInstance == null)
            {
                blockInstance = new BlockInstance
                {
                    cardAttacker = cardAttacker
                };
                _blockInstances.Add(cardAttacker, blockInstance);
            }

            if (!blockInstance.cardBlockers.Contains(cardBlocker))
            {
                blockInstance.cardBlockers.Add(cardBlocker);
                cardBlocker.wasUsed = true;
            }

            count = blockInstance.cardBlockers.Count;
        }