Wash Away — ruling 1

Copies of spells are never cast from a player's hand, so Wash Away can counter copies of spells even if its cleave cost wasn't paid, regardless of whether the original spell being copied was cast from a player's hand.

Wash Away — ruling 2

If you cast a spell for its cleave cost, that spell doesn't have any of the text in square brackets while it's on the stack.

Wash Away — ruling 3

A cleave cost is an alternative cost that's paid instead of the spell's mana cost. Casting a spell for its cleave cost doesn't change the spell's mana value.

Wash Away — ruling 4

You can't cast a spell for both its cleave cost and another alternative cost. For example, if an effect gives an Alchemist's Retrieval in your graveyard a flashback cost of {U}, you can't cast it from your graveyard for its cleave cost.

Wash Away — ruling 5

If an effect allows you to “cast a spell without paying its mana cost,” you can't cast that spell for its cleave cost.

Wash Away : règles, fonctionnement et interactions (MTG)

Wash Away 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

Cleave (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.) Counter target spell [that wasn't cast from its owner's hand].

How it works : Wash Away

Original English text — Wizards of the Coast / Scryfall

#1November 19, 2021· Wizards of the Coast
Copies of spells are never cast from a player's hand, so Wash Away can counter copies of spells even if its cleave cost wasn't paid, regardless of whether the original spell being copied was cast from a player's hand.
No other card is named in this ruling.
#2November 19, 2021· Wizards of the Coast
If you cast a spell for its cleave cost, that spell doesn't have any of the text in square brackets while it's on the stack.
No other card is named in this ruling.
#3November 19, 2021· Wizards of the Coast
A cleave cost is an alternative cost that's paid instead of the spell's mana cost. Casting a spell for its cleave cost doesn't change the spell's mana value.
No other card is named in this ruling.
#4November 19, 2021· Wizards of the Coast
You can't cast a spell for both its cleave cost and another alternative cost. For example, if an effect gives an Alchemist's Retrieval in your graveyard a flashback cost of , you can't cast it from your graveyard for its cleave cost.
No other card is named in this ruling.
#5November 19, 2021· Wizards of the Coast
If an effect allows you to “cast a spell without paying its mana cost,” you can't cast that spell for its cleave cost.
No other card is named in this ruling.