The 3e warlock is a weird class. When it got released so many pearls were clutched, and everyone swore it was overpowered. Then once people played it, they realized it actually was kind of OK, and even when hardcore optimized, you were sitting at a Rogue power level (now known as high), or a T4 class if you like that system more. Hardly OP, and potentially falling behind depending on your build. You’d still see a DM who banned them for being OP, but that was also a clear indicator that the DM had never seen one in play, or was also probably banning most casters who did anything but magic missile wizards or healbot clerics (two of the most powerful classes in the game, with two of the least powerful builds in the game).
Out of the box, a warlock is throwing a single attack, basically guaranteed to hit, at a range, for moderate to low damage. It also has a couple of powers that are probably pretty fun for exploration and RP if you pick the right ones, like unlimited invisibility and flight, or are a waste of time, if you pick one of the others. If you optimize your warlock, you can turn that moderate to low damage into essentially an auto-kill against one opponent per round. In 3e rocket tag, that’s a viable life choice, but it takes a lot of effort, and isn’t really comparable when your top tier characters are throwing out mass save or dies that drop the entire enemy team in one round, or before the first round.
So even though the warlock isn’t amazing, its cool. Why is it cool? It gets to fire kamehameha’s at will, and do some magic without having to deal with 3e’s complex spell system. You learn a couple of notspells, and can just do them whenever you want. In practice, it’s a blast to play, and the flavor is super cool. Unfortunatly, 3e had a couple of similar classes that tried to dip the same flavor, but they were all garbage. What this means, is that I’m always trying to find some way to work the cool parts of warlock (kamehamehas) into my characters, without being limited by the classes other sub par features. If you don’t min-max eldritch blast (the Kamehameha), it’s not particularly better than an evoker, but it sweet. Unfortunatly, 3e never really “finished” the devoted ___ line of feats. These feats let you stack multi-classed levels to determine your powers for some iconic class features. Devoted Tracker lets you stack paladin and ranger levels for parts of smite evil, wild empathy, animal companion, and paladin’s mount, for example. So you could be a ranger 4/paladin 4 who has an 8th level paladin’s mount. A nice way to build an effective nature paladin without hoping you can find a perfect prestige class or whatever.
The problem with the Devoted feats, is they are super specific. 3e doesn’t have 13 clases like 5e. It’s got over 50 according to some lists I was googling. Who knows though, because is a wildshape ranger the same class as a ranger? Depending on who built that list of 50, the answer changes. There’s no realistic way to build a combo feat for every class combo. Instead, I’m going to propose a couple of broad reaching feats in the vein of the devotees that finally allow me to play the fighter who kamehameha’s I’ve always wanted.
Prerequisite: Base attack bonus +5
You gain the eldritch blast abilities of a warlock of your level. You do not gain knowledge of any invocations. If you have levels in a class that grants eldritch blast, you can instead choose to increase the eldritch blast damage by 2d6.
Prerequisite: 1d6 Eldritch Blast.
You add the warlocks list of invocations to your classes list of invocations. If your class doesn’t give invocations, it now does. In addition, you learn a single Least invocation of your choice. Additionally, at level 6, you gain access to lesser invocations, at level 11 you gain access to greater invocations, and at 16 you gain access to dark invocations. Each time you gain access to more powerful invocations, you can exchange the invocation gained by this feat for a different one you are eligible for.
Special: Once you have this feat, you can take the Extra Invocations feat to gain more invocations known.
Prerequisites: Eldritch Blast.
As a swift action, you can form your eldritch blast into a weapon you are proficient with. This weapon lasts for a number of rounds equal to your character level, and functions exactly like the base weapon of its shape with a few exceptions. First, all attacks made with your Eldritch Blade are touch attacks. Second, the weapons base damage is replaced by your Eldritch Blast damage die. So, an eldritch great sword wielded by a Warlock with 4d6 Eldritch Blast damage, and 18 strength would deal 4d6+6 19-20 x2. Third, you can only have one eldritch blade at a time and attempts to summon a new one cause the old to dissipate. The Eldritch Blade can be modified by your invocations, feats, items, and other abilities as if it were an Eldritch Blast. Lastly, if your Eldritch Blade is a thrown weapon, you can summon 10 of them as a single swift action.