26 cards where (the card types include “basic” or (the card types include “cave” and the cards don’t transform))

Captivating Cave (The Lost Caverns of Ixalan #268)
Cavernous Maw (The Lost Caverns of Ixalan #270)
Echoing Deeps (The Lost Caverns of Ixalan #271)
Forest (Outlaws of Thunder Junction #285)
Forgotten Monument (The Lost Caverns of Ixalan #272)
Hidden Cataract (The Lost Caverns of Ixalan #273)
Hidden Courtyard (The Lost Caverns of Ixalan #274)
Hidden Necropolis (The Lost Caverns of Ixalan #275)
Hidden Nursery (The Lost Caverns of Ixalan #276)
Hidden Volcano (The Lost Caverns of Ixalan #277)
Island (Outlaws of Thunder Junction #279)
Mountain (Outlaws of Thunder Junction #283)
Pit of Offerings (The Lost Caverns of Ixalan #278)
Plains (Outlaws of Thunder Junction #277)
Promising Vein (The Lost Caverns of Ixalan #279)
Snow-Covered Forest (Kaldheim #284)
Snow-Covered Island (Kaldheim #278)
Snow-Covered Mountain (Kaldheim #282)
Snow-Covered Plains (Kaldheim #276)
Snow-Covered Swamp (Kaldheim #280)
Snow-Covered Wastes (Modern Horizons 3 #229)
Sunken Citadel (The Lost Caverns of Ixalan #285)
Swamp (Outlaws of Thunder Junction #281)
Urza's Cave (Modern Horizons 3 #234)
Volatile Fault (The Lost Caverns of Ixalan #286)
Wastes (Commander Masters #1055)

The message was clear to Sorin—time to search for something else.