Thancred Waters — ruling 1

If Thancred Waters leaves the battlefield or you lose control of it before its triggered ability resolves, the target legendary permanent won't gain indestructible at all.

Thancred Waters — ruling 2

Thancred Waters's last ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered or otherwise leaves the stack.

Thancred Waters : règles, fonctionnement et interactions (MTG)

Thancred Waters 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

Flash Royal Guard — When Thancred Waters enters, another target legendary permanent you control gains indestructible for as long as you control Thancred Waters. Whenever you cast a noncreature spell, Thancred Waters gains indestructible until end of turn.

How it works : Thancred Waters

Original English text — Wizards of the Coast / Scryfall

#1June 6, 2025· Wizards of the Coast
If Thancred Waters leaves the battlefield or you lose control of it before its triggered ability resolves, the target legendary permanent won't gain indestructible at all.
No other card is named in this ruling.
#2June 6, 2025· Wizards of the Coast
Thancred Waters's last ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered or otherwise leaves the stack.
No other card is named in this ruling.