Undying Servitude is a perfectly fine bonus summoning option for necromantic warlocks when you get it. As you get higher and higher level, these will start to feel closer to Unseen Servants in usefulness than actual summoned monsters through Conjure or Summon spells.

If you want to be the slipperiest little warlock there ever was, Trickster’s Escape can be a part of that fantasy. I think there are better ways to get there, but Freedom of Movement does do what it says on the tin and won’t feel as bad as normal when you’re getting a special spell slot just for it instead of needing it to compete with other 4th level options. 

Tomb of Levistus is hard to use well, and when overused will actively detract from your team's ability to win by wasting your turns inside a devil’s popsicle. At its best, though, Tomb of Levistus is the kind of feature that can best some of the most dangerous damaging abilities in the game in a way nearly no other feature can.

Thirsting Blade is an invocation for the combat weapon based warlocks out there. This will often be the only invocation I pick up dedicated to martial warlock builds if I’m staying for a while in the warlock class and really want to kill stuff with a greatsword or longbow.

Thief of Five Fates teaches you the Bane spell, but then only lets you cast it once a long rest for some reason. That isn’t good enough for an invocation. It doesn’t give you more things to do, it lets an already hyper competitive resource have even more competition, but the competition it's adding is Bane. 

Sign of Ill Omen is everything wrong with the warlock class. It's an incredibly inefficient way to do something no other class even wants to do, but if they do decide to, they do it at a far cheaper price.

Shroud of Shadow is edgy and cool, and a dozen different warlock archetypes desperately want Invisibility at will for aesthetic reasons, but the mechanics behind it make it clunky and unwieldy.

Sculptor of Flesh isn’t giving you access to more resources, nor is it meaningfully empowering a resource you already have. It lets you get access to a spell bards, druids, sorcerers, and wizards can just learn and cast with their 4th level slots while also having a robust roster of lower level spells to play with.

The crux of Repelling Blast is it gives you a no save 10 ft. shove on every Eldritch Blast. Unlike the pull you get with Grasp of Hadar or the slowing effect you get with Lance of Lethargy, Repelling Blast affects each and every blast of energy fired.

Hexblades opened up a new way for melee warlocks to exist in a way that prior had been… a little unsatisfying. Relentless Hex carries forward this idea, giving Hex based melee warlocks and hexblades a brand new toy to play with while doing their Hex thing. 

Rebuke of the Talisman gives you a reason to stick it on somebody other than yourself if you’re a ranged warlock, which is nifty, and a reason to want to take damage for some melee warlock builds. This, to me, needs to be a base feature of the pact, not an expanded invocation, especially given the reactive nature of it.

Protection of the Talisman just stacks a Resistance-like effect on the talisman as well. Adding a d4 to potentially turn a failed save into a success is fine. Getting to do that three to four times a long rest is probably all you’ll ever need. Being able to only ever affect one creature with it at a time without having to move the talisman around is just... bad.

Otherworldly Leap has so much potential. This could be an exceptional warlock option for the early tier to offer some fun, engaging, otherworldly exploration. Without the prerequisites, before everyone is getting access to flight and teleportation nonsense, Jump could open up your barbarians and fighters to make massive long jumps.

One with Shadows is a super nifty little trick warlocks can pick up at 5th level. This is a pseudo-Invisibility at will, given you can be in some area of dim light or darkness. As soon as you read this, gears start turning in your brain, figuring out how best to weaponize and utilize free at will Invisibility with the caveat that you can’t move or take any actions or reactions

Misty Visions takes Minor Illusion and pumps it up to 11. This is the illusionist fantasy the illusionist wizard wishes they had. If you’ve got a need to mess around with reality and sell outrageous lies, Silent Image at will absolutely is a tool you want to have, and Misty Visions gives you exactly that. 

Mire the Mind is an embarrassment of an invocation. You can’t afford this on warlocks. It gives you a spell you’re not going to want to cast with your pact magic slots, then gates it to once a long rest anyway. This is worse than learning a spell that is bad on warlocks.

Minions of Chaos is not worth an invocation, not even close. Like Thief of Five Fates, all it does is functionally teach you a spell, then gate your usage to it to once a long rest instead of just letting you use your regular spell slots on it.

If Master of Myriad Forms just gave you all three of the Alter Self abilities you could toggle on and off at will, I’d say it was fine, but shouldn’t have the outrageous 15th level prerequisite. As it stands, I wouldn’t even recommend it for builds that could get it at 2nd level for long term play, as there are other cheap and effective ways to get these effects without eating your concentration.

Mask of Many Faces can sire hundreds of character concepts. The Assassin rogue archetype comes with a bunch of fake identities with their Infiltration Expertise, as does the Charleton background with its False Identity. Now, imagine taking this idea of fake personas and getting to adopt an infinite number of appearances of your choice.

Hexblades, oh Hexblades. Wizards of the Coast’s apology for the atrocious Pact of the Blade feature. Maddening Hex comes in alongside it as an expandable way to embolden the “curse” based warlock fantasy.