44 cards where the illustration contains “buttress”

Aragorn, the Uniter (The Lord of the Rings: Tales of Middle-earth #192)
Boromir, Gondor's Hope (Tales of Middle-earth Commander #49)
Builder's Blessing (Avacyn Restored #8)
Cabal Coffers (Tales of Middle-earth Commander #360)
Captain of Umbar (The Lord of the Rings: Tales of Middle-earth #45)
Command Tower (Tales of Middle-earth Commander #301)
District Guide (Guilds of Ravnica #128)
Forest (War of the Spark #264)
Forest (Guilds of Ravnica #264)
Forest (Return to Ravnica #273)
Forest (Ravnica: City of Guilds #306)
Forest (Arena League 2006 #5)
Gate Colossus (Ravnica Allegiance Promos #232)
Gateway Plaza (Guilds of Ravnica #247)
Hallowed Fountain (Dissension #174)
Hired Poisoner (Guilds of Ravnica #72)
Human (Ravnica Allegiance Tokens #1)
Island (Ravnica: City of Guilds #292)
Island (GRN Guild Kit #24)
Kor Haven (Tales of Middle-earth Commander #368)
Mana Confluence (Commander Legends #721)
Maze's End (Dragon's Maze #152)
Minas Tirith (The Lord of the Rings: Tales of Middle-earth #256)
Minas Tirith (The Lord of the Rings: Tales of Middle-earth #341)
Minas Tirith (The Lord of the Rings: Tales of Middle-earth #420)
Mountain (RNA Ravnica Weekend #B06)
New Benalia (Future Sight #172)
Orzhov Guildgate (Ravnica Allegiance #252)
Plains (Guilds of Ravnica #260)
Plains (Ravnica: City of Guilds #290)
Port Town (Tales of Middle-earth Commander #323)
Protector of Gondor (The Lord of the Rings: Tales of Middle-earth #25)
Rammas Echor, Ancient Shield (Tales of Middle-earth Commander #505)
Rescue (Urza's Destiny #44)
Selesnya Guildgate (Guilds of Ravnica #255)
Selesnya Guildgate (Modern Masters 2017 #246)
Shinka, the Bloodsoaked Keep (Tales of Middle-earth Commander #374)
Skarrg Goliath (Gatecrash #133)
Stomping Ground (Gatecrash #247)
Swamp (Duel Decks: Jace vs. Vraska #82)
Temple Garden (Return to Ravnica #248)
Urban Utopia (Guilds of Ravnica #146)
Watery Grave (Guilds of Ravnica #259)
Watery Grave (Magic Online Promos #72299)

Though this query has ended, its relics still slumber in New Argive.