Ionizing Blast (3.5e Invocation)
From D&D Wiki
|Greater; 6th; Eldritch Essence|
This eldritch essence invocation allows you to change your eldritch blast into a ionizing blast. A ionizing blast changes the invoker's eldritch blast to electricity damage.
In addition, creatures struck by an ionizing blast must make a Reflex save or be entangled for one minute as their muscles lock up from the electrical discharge.