Berserk Hammer (5e Equipment)
From D&D Wiki
Weapon (warhammer), uncommon
The berserk hammer is a modified warhammer that is said to break hordes.
You can use your action to smash your berserk hammer into the ground. All creatures within a 10-foot radius of you must succeed on a Strength saving throw or fall prone. The DC is 8 + your Strength modifier + your proficiency bonus. A Large or larger creature automatically succeeds on this saving throw.