How does combining eldritch essence and shape with metamagic feats effect the spell level?

Question

In the Complete Arcane, page 9, it indicates:

When a warlock uses both kinds of invocations to alter an eldritch blast, the spell level equivalent is equal to the spell level of the eldritch blast, the level of the eldritch essence invocation, or the level of the blast shape invocation, whichever is higher.

Therefore if a warlock combines Eldritch Chain (Shape - 4th level) as well as Brimstone Blast (Essence - 3rd level), it will be as if casting a 4th level spell if I am understanding correctly since shape and essence levels don't stack together, and just take the whichever is higher.

Using Maximize spell-like ability on Eldritch blast requires CL to be at least 6 since, Eldritch blast is a 1st level spell and the formula is [(CL/2) - 2].

By that, can a 6th level warlock cast Eldritch Chain with Brimstone essence combined with Maximize spell like ability? Or do I need to re-calculate the spell according to maximize-spell like abilities formula, which would require CL 12?

Answer 1

You should re-calculate minimal caster level required

Eldritch Blast says the following about its own effective spell level:

If you apply a blast shape or eldritch essence invocation to your eldritch blast, your eldritch blast uses the level equivalent of the shape or essence.

^{emphasis mine}

Maximize spell-like ability checks effective spell level of an ability it affects, and applies at a time of using of a mentioned ability, so your now-effectively-fourth-level spell-like ability requires accordingly high caster level for this one particular usage.