Hydroblast — ruling 1

Hydroblast can target any spell or permanent, not just a red one. It checks the color of the target only on resolution.

Hydroblast — ruling 2

The decision to counter a spell or destroy a permanent is a decision made on announcement before the target is selected. If the spell is redirected, this mode can't be changed, so only targets of the selected type are valid.

Hydroblast : règles, fonctionnement et interactions (MTG)

Hydroblast 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

Choose one — • Counter target spell if it's red. • Destroy target permanent if it's red.

How it works : Hydroblast

Original English text — Wizards of the Coast / Scryfall

#1June 8, 2016· Wizards of the Coast
Hydroblast can target any spell or permanent, not just a red one. It checks the color of the target only on resolution.
No other card is named in this ruling.
#2October 4, 2004· Wizards of the Coast
The decision to counter a spell or destroy a permanent is a decision made on announcement before the target is selected. If the spell is redirected, this mode can't be changed, so only targets of the selected type are valid.
No other card is named in this ruling.