Where did I see this extra attack ability?

[ericthecleric]

Within the last few months, I remember reading about an ability that grants an extra attack a round, even if the creature only uses a standard action in the round. I can't remember if it is a monster special attack, something from a template, or something else.

Does anyone know what I'm talking about?

[Wheldrake]

Could it be one of the mythic path abilities? Those certainly allow extra attacks.

[Backpack]

5ed fighter action surge maybe?

[CBDunkerson]

Cleave?
Startoss Style?

Could be a lot of things.