Empower spell does this:
EMPOWER SPELL-LIKE ABILITY [GENERAL]
Prerequisite: Spell-like ability at caster level 6th or higher.
Benefit:
Choose one of the creature’s spell-like abilities, subject to the
restrictions below. The creature can use that ability as an empowered
spell-like ability three times per day (or less, if the ability is
normally usable only once or twice per day).
When a creature uses
an empowered spell-like ability, all variable, numeric effects of the
spell-like ability are increased by one half. Saving throws and opposed
rolls are not affected. Spell-like abilities without random variables
are not affected.
The creature can only select a spell-like
ability duplicating a spell with a level less than or equal to half its
caster level (round down) –2. For a summary, see the table in the
description of the Quicken Spell-Like Ability feat.
Special:
This feat can be taken multiple times. Each time it is taken, the
creature can apply it to a different one of its spell-like abilities.
Does this mean that I have to drop levels of my Eldritch blast to use it? It's worth dropping a d6 to add 1.5 times 6d6 or does it effect the invocations I can use with the EB?
I'm looking at doing the following with the EB: 8d6 dmg as lvl 12 warlock with chuasible greater + 2d6 for vitrolic blast + Eldritch chain for a spell level of 6th (6th for EB + 6th for VB and 4th for EC) would I have to drop the EB to 4th if I wanted to use the Empower spell like ability? or would I have to drop it to a 1st lvl spell which would be down from 6d6 (basic EB) to 1d6 + the chusible?