Fortunately, there are hundreds of them, so finding enough to play even in a singleton format such as Commander won't prove too difficult
Thats the new total cost of the card, and you can delve up to five cards to pay this additional cost since it now costs 5 generic mana instead of 4
If for some reason this isn't possible, please contact Wizards of the Coast customer support for more information
Monastery Mentor proved itself to be one of the best finishers in older formats like Vintage, where it's easy to chain together cheap spells and cantrips to potentially make a lethal army of prowess tokens in just a single turn, which is certainly strong but still doesn't really feel broken to me
Of course, selling online comes with its own risks
Unidentified Hovership: Abduct opposing creatures, and ensure they wont return with the Unidentified Hovership, and grab a card if Tails is out