Convulsions of the World
Cause a tremor to knock prone creatures within 20 feet, with some immune.
Prerequisite: 3rd level
Your mind reaches deep into the ground and an elder voice answers. You can use an action to cause a localized tremor to shake the ground around you. Each creature other than yourself within 20 feet of you must succeed on a Dexterity saving throw or be knocked prone. You can choose a number of creatures equal to half your proficiency bonus to automatically succeed on this saving throw. You must finish a long rest before you can use this invocation again.
Source and licence
From Tome of Heroes.
Licence: Open Game Content (OGL 1.0a).