58 cards where the illustration contains “tunnel”

Chittering Rats (Magic Online Promos #62445)
Chromatic Sphere (Invasion #299)
Construct (Conspiracy: Take the Crown Tokens #12)
Cover of Darkness (Onslaught #133)
Crypt Lurker (Core Set 2021 #93)
Culvert Ambusher (Murders at Karlov Manor #158)
Darkbore Pathway // Slitherbore Pathway (Secret Lair: Ultimate Edition #17)
Darkbore Pathway // Slitherbore Pathway (Secret Lair: Ultimate Edition #17)
Dark Ritual (Limited Edition Alpha #98)
Deeproot Pilgrimage (The Lost Caverns of Ixalan #52)
Dimir Aqueduct (Ravnica: City of Guilds #276)
Dowsing Device // Geode Grotto (The Lost Caverns of Ixalan #146)
Dowsing Device // Geode Grotto (The Lost Caverns of Ixalan #146)
Dreadbore (Return to Ravnica #157)
Duct Crawler (Stronghold #79)
Dwarf (Throne of Eldraine Tokens #7)
Dwarven Driller (Judgment #85)
Flatline (Doctor Who #648)
Forest (Secret Lair Drop #395)
Gamble (Eternal Masters #132)
Goblin Grenade (Fallen Empires #56c)
Goblin Spelunkers (Seventh Edition #193)
Goblin War Party (Modern Horizons #131)
Grim Contest (Fate Reforged #153)
Izoni, Thousand-Eyed (GRN Guild Kit #50)
Izzet Guildgate (Guilds of Ravnica #251)
Izzet Guildgate (Guilds of Ravnica #252)
Korozda Gorgon (Dragon's Maze #78)
Kozilek's Sentinel (Battle for Zendikar #129)
Lava Tubes (Ice Age #358)
Learn from the Past (Dragons of Tarkir #60)
Masterful Replication (Core Set 2020 #65)
Metallic Sliver (Time Spiral Remastered Tokens #15)
Midnight Reaper (Guilds of Ravnica #77)
Ogre (Worldwake Tokens #3)
Out Cold (Murders at Karlov Manor #66)
Pincer Spider (Invasion #201)
Relentless Advance (War of the Spark #64)
Sepulcher Ghoul (Adventures in the Forgotten Realms #118)
Sepulcher Ghoul // Sepulcher Ghoul (Adventures in the Forgotten Realms Art Series #18)
Sepulcher Ghoul // Sepulcher Ghoul (Adventures in the Forgotten Realms Art Series #18)
Severed Strands (Guilds of Ravnica #85)
Sewer Shambler (Return to Ravnica #75)
Shelob, Dread Weaver (Tales of Middle-earth Commander #29)
Skirk Prospector (Onslaught #230)
Spinal Centipede (Guilds of Ravnica #86)
Steamflogger of the Month (Unstable #94)
Strip Mine (Zendikar Expeditions #43)
Treasure Hunt (Worldwake #42)
Tunnel (Limited Edition Alpha #178)
Tunnel Tipster (Murders at Karlov Manor #180)
Undercity Sewers (Murders at Karlov Manor #270)
Undercover Crocodelf (Murders at Karlov Manor #239)
Underworld Connections (Return to Ravnica #83)
Unstable Glyphbridge // Sandswirl Wanderglyph (The Lost Caverns of Ixalan #41)
Unstable Glyphbridge // Sandswirl Wanderglyph (The Lost Caverns of Ixalan #41)
Varolz, the Scar-Striped (Dragon's Maze #112)
Veiled Crocodile (Urza's Saga #108)
Vindictive Mob (Ravnica: City of Guilds #112)
Vraska's Stoneglare (Guilds of Ravnica #272)
Vug Lizard (Urza's Saga #227)
Xantcha, Sleeper Agent (Commander 2018 #50)

This search is finished. Now the real work can begin.