Group menace loadout

I use mental and can’t find out how some players are using group menace.

Menace is a Weapon Buff, specifically for Mental. It is not a group buff. It only applies the buff to whoever uses the ability.

If you're looking for the group weapon buff it's called Psychic Empowerment.

Uh yeah there is I ve seen it many times activated while im playing.

Then you're seeing something else. All controller powers only have the one group weapon buff.