Thorny Blast (Warlock Invocation)

Prerequisite(s): eldritch blast cantrip, Pact of Thorns

You can cast eldritch blast as a flying tendril of phantasmal thorns. The damage type becomes magical piercing. A target that is hit must make a Strength saving throw; on a failed saving throw it is restrained for 1 minute. A creature restrained by the thorns can use its action to make a Strength check against your spell save DC. On a success, it frees itself. This invocation cannot be used in conjunction with an invocation that changes the base damage of eldritch blast to a damage type other than piercing.