Saprazzan Legate 

Creature — Merfolk Soldier
If an opponent controls a Mountain and you control an Island, you may cast this spell without paying its mana cost.
Flying
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Cards that do something similar expected a card that isn't here?
Reports become test cases the matcher is graded against before an update ships. Delvefall isn't a chatbot guessing, it compares the printed rules text of every card with plain math, and examples like yours decide which differences should count.
Mogg Salvage 99%
$0.24#6528
"If an opponent controls an Island and you control a Mountain, you may cast this spell without paying its mana cost."
Sivvi's Ruse 89%
$0.19#26312
"If an opponent controls a Mountain and you control a Plains, you may cast this spell without paying its mana cost."
Kyren Legate 87%
$0.30#27488
"If an opponent controls a Plains and you control a Mountain, you may cast this spell without paying its mana cost."
Rushwood Legate 81%
$0.27#29487
"If an opponent controls an Island and you control a Forest, you may cast this spell without paying its mana cost."