Night Brushwagg Ringmaster

Persist is a triggered ability. “Persist” means “When this permanent is put into a graveyard from the battlefield, if it had no -1/-1 counters on it, return it to the battlefield under its owner’s control with a -1/-1 counter on it.”

Menace is an evasion ability.

A creature with menace can’t be blocked except by two or more creatures. (See rule 509, “Declare Blockers Step.”)

Multiple instances of menace on the same creature are redundant.