The Gold tier was relatively easy to manage, but as we proceeded, reaching the Crystal tier would require killing those at the Amethyst tier, and to reach the Amethyst tier, one would have to kill a Diamond tier. Once reaching the Diamond tier, I fear only the Nine Great Experts could be targeted. However, there are only nine such experts. Where can one find so many to kill?
Therefore, as of now, the Xuanming White Bone Banner is rather useless, and it will remain that way in the future. Hoping to resist with the Skeleton Sea and the Giant Dragon seems incredibly unlikely. The vast gap cannot be bridged by sheer numbers.
Nonetheless, if it were to be used for mining ores, then there could be nothing better. There are no more suitable candidates than these tireless fellows. As the Sky-opening Axe continues to be repaired, in the future, it could summon nine thousand, ninety thousand, or even millions of skeletons!