Hello!

Under normal circumstances, when strengthening, regardless of success or failure, the strengthened secondary card will disappear. If the strengthened card is a 6-star or above card, it will be downgraded if it fails.

The function of the insurance money is that if a strong card fails, it will not be downgraded. For cards above 6 stars, the higher the star rating, the greater the insurance money. The secondary card will also disappear, but the main card will not disappear

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Extended reading: How to buy insurance, which one is better, and step-by-step instructions to avoid these "pitfalls" of insurance