Warlock Options...

[weckar]

Is there any way for a Warlock to gain access to any Gish PrC (good or not) or to the Sacred Exorcist PrC?

It's for a thing. Basically a Warlock with a focus on killing undead and spirits in particular...

[Pluto!]

Cyran Avenger (http://archive.wizards.com/default.asp?x=dnd/iw/20050707b&page=2) and Impure Prince (Magic of Eberron) have full BA and 4/5 casting for 5 levels. Dragonslayer has full BA/casting for 1 level.

After those, the options get sketchier.

[Red Fel]

Is there any way for a Warlock to gain access to any Gish PrC (good or not) or to the Sacred Exorcist PrC?

It's for a thing. Basically a Warlock with a focus on killing undead and spirits in particular...

Sacred Exorcist is tricky, because of the spell requirements (Dismissal or Dispel Evil, both of which are 4th-level spells).

There is a class that fits the fluff of a Warlock who slays undead and spirits - it's the Enlightened Spirit class from Complete Mage. It grants you a flight invocation for free, several protective benefits, a blast that deals bonus damage to undead (and ignores incorporeal miss chance), a blast that deals bonus damage to Evil Outsiders (and acts as Dimensional Anchor), and the ability to deliver targeted Greater Dispel Magic with a touch. The big cost, however, is that your invocation progression pretty much stops.

Now, there are ways to gish up a Warlock, if you're up for a bit of cheese. One popular method is to use Eldritch Claws and Beast Strike from Dragon Magazine.

Eldritch Claws allows you to form claw weapons that deal your Eldritch Blast + Unarmed Strike in damage. However, because they're claws, you don't get iterative attacks with them, making them inferior to Eldritch Glaive for melee purposes.

That's where Beast Strike comes in. Beast Strike requires a slam or claw attack (such as the claw attack Eldritch Claws gives you), and adds that damage to your ordinary iterative unarmed strikes. This means that, with both feats, you deal Unarmed Strike + (Eldritch Blast + Unarmed Strike) with your unarmed attacks, which can be surprisingly impressive. With the right invocations and a few dips, you can actually be a surprisingly capable (if a bit squishy) gish.

Additional cheese could potentially apply your Eldritch Claw damage to other weapons, but risks having books thrown at you.

If you're interested in other melee Warlock options, consider reading the handbook (http://www.giantitp.com/forums/showthread.php?159708-Shinken-s-Guide-to-Melee-Warlocks).

[weckar]

Cyran Avenger is interesting. The capstone ability will take a ton on DM talking though. Other than that the abilities are okay, I guess (I already have SwD at will, kind of).

Impure Prince is just too weird.

EDIT: were the requirements for Verdant Lord ever updated? Because that seems rather perfect...