Wall of Shadows — ruling 1

Can be targeted by a modal spell that can target a non-Wall in one of its modes, even if it has a mode that targets only Walls. That spell can, in theory, target a non-Wall, so it is not a “spell that can target only Walls”.

Wall of Shadows : règles, fonctionnement et interactions (MTG)

Wall of Shadows is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Defender (This creature can't attack.) Prevent all damage that would be dealt to this creature by creatures it's blocking. This creature can't be the target of spells that can target only Walls or of abilities that can target only Walls.

How it works : Wall of Shadows

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
Can be targeted by a modal spell that can target a non-Wall in one of its modes, even if it has a mode that targets only Walls. That spell can, in theory, target a non-Wall, so it is not a “spell that can target only Walls”.
No other card is named in this ruling.