Anthex, Trigger Counter

Anthex, Trigger Counter can't be countered.
{u/b}, {t}: Counter target creature spell. Surveil 3.
(Look at the top three cards of your library, then put
any number of them into your graveyard and the rest
on top of your library in any order.)
As long as Anthex is tapped, if a triggered ability
of another creature you control would trigger,
that ability triggers an additional time.