This eldritch essence invocation allows you to change your eldritch blast into a beshadowed blast. Any living creature struck by a beshadowed blast must succeed on a Fortitude save or be blinded for 1 round + an extra round per 2 warlock levels. When greater invocations are known, the blast can now affect one of the following, blindsense or and blind sight or tremorsense. When dark invocations are know you may choose another ability to affectknown tremorsense is affected.