There seems to be no rhyme nor reason
Masterpiece Series MTG: Exceptionally rare, alternate-art foil versions of powerful cards, like the Kaladesh Inventions or Amonkhet Invocations
But she fared even worse there
Creatures (27) 4 Mother of Runes 2 Mangara of Corondor 2 Aven Mindcensor 3 Flickerwisp 4 Stoneforge Mystic 3 Mirran Crusader 4 Phyrexian Revoker 1 Fiend Hunter 4 Thalia, Guardian of Thraben Lands (23) Spells (10) Decks like Ari Laxs Death and Taxes could use Mother of Runes to pressure opposing removal spells, protect ones self from opposing attacks, or just force through some damage
10 | Boltwave: $2.88 Its rare that a new burn spell is printed that can compete with the established titans of the genre, but Boltwave is exactly that
That means youll be able to duplicate this 1/2 Otters ETB ability which is pretty much just a noncreature, nonland Impulse (look at the top four of your library, put one in hand and rest on the bottom of your library)