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.
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.
6 Jun 2025
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.