Untappers are always useful whether straight up in decks with commanders like Reveka, Wizard Savant, Stitcher Geralf, or Merieke Ri Berit as commanders, or as special case in Prime Speaker Vannifar decks for Fatestitcher
The contents can vary and are generally focused on a theme, yet low-powered with no specified format
One, it grants all your noncreature spells convoke, so you can use your creatures to cast them
The other two card types provide other ways to affect the game
Make sure to pay attention to these differences when you buy non-Standard sets so that you have a full understanding of what to buy
Mould isn't something you'd normally associate with monsters, but while fungus monsters won't show up all that often in the series, I appreciate this first one