Minotaur is one of the two skins released in the third part of the Mr. Bones' Vitality Stash offer. It could be purchased as part of an item deal for a limited time in late October 2018.
Minotaur could be purchased for $7.99 in the "Deal of the Year!" which included 25000 coins, 1200 DNA and Silent Nun skin. This skin was not available for individual purchase and may not be available for purchase in the future.
Details of this skin may vary depending on location, platform or time.
Note: The third part of the Mr. Bones' Vitality Stash was released again for limited times in early November 2019 and then in early November 2020. The included skins and items remained the same for the Deal of the Year. However, the price changed from $9.99 in 2019 to $7.99 in 2020.