You shouldnt have trouble purchasing them
Frequently, Cavern of Souls shows up in tribal decks, such as Humans, Spirits, and Elementals, but that hasnt stopped Amulet Titan and other decks from playing it to force through specific high-value creatures
The reason to play these cards is creature synergy
WOE Witches Wilds of Eldraine featured a trio witches (aura commander Eriette of the Charmed Apple, stun commander Hylda of the Icy Crown, and activated ability commander Agatha of the Vile Cauldron), and they along with Talion, the Kindly Lord are responsible for a curse thats affecting the plane, which am I the only one getting Far Cry 5 vibes
The other is the Arcbond combo
The Rise of Sozin / Fire Lord Sozin Fire Lord Sozin is the real reason we're here and boy is the payoff for dealing saboteur damage worth the backstory