The skill is called Val XX, which can be used to get peace in corrupt areas, or it can be played in the back. This can't be replaced by ordinary stones, and then when you upgrade to 20 grades and 20% quality, you can count it with a currency called Val Zhu Bao, and the chances are the same, one grade will be lowered, one grade will be upgraded, any quality will be lowered, and any quality will be improved (up to 3%). Among them, upgrading one level and improving the quality of 23 will break through the upper limit of the original skill stone and will be greatly improved. Then, this skill stone that has used Valbaozhu will be marked as corrupted in the bottom red letter, so that this stone can no longer gain upgrading experience or improve quality.