Monolith: TFT Set 18 trait
Monolith is a single-unit trait in TFT Set 18: it belongs to Malphite and is active as soon as Malphite is on the board.
What Monolith does
Monoliths gain 10 Armor and Magic Resist for each enemy targeting them.
From Riot's game data, with the latest patch notes applied; the exact numbers can change between patches.
Malphite