Frenzied Gorespawn

When this creature enters, for each opponent, goad target creature that player controls. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)
Whenever one or more creatures attack one of your opponents, those creatures gain menace until end of turn.

Ravnica: Clue Edition

When Frenzied Gorespawn enters the battlefield, for each opponent, goad target creature that player controls. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)
Whenever one or more creatures attack one of your opponents, those creatures gain menace until end of turn.

Creatures your opponents control attacking one of your opponents will cause Frenzied Gorespawn's ability to trigger.

Only creatures attacking your opponents will gain menace until end of turn. Creatures attacking planeswalkers or battles won't gain menace, no matter who controls or protects those permanents.