Hercules Beetle

The wording talks about minions, but the damage bonus applies to whips and sentries as well. That matters because most summoner builds past Plantera spend more time cracking enemies with a whip than they do standing still, and the accessory is quietly boosting that too.

Extra minion knockback is mostly good: staggered enemies stop closing on you and your other minions get free time on target. It works against you in one situation, which is a chokepoint farm where you want everything piled up. Bosses ignore it entirely, so treat it as a damage accessory when you plan a boss loadout.

The Witch Doctor only offers it if you talk to him while he lives in the jungle, so a temporary house out there is enough to unlock the sale. Once you have it, do not sell the old one when you upgrade: it is the base for the Papyrus Scarab alongside the Necromantic Scroll, and it is a straight step up from the Summoner Emblem if you have been running that.