So, I'm sure if people know me, you'll likely know that I am not a fan of Warlocks. In the past I have called them a poor class after having seen them on paper, despite having never played one. Well, part of that has finally changed. I played a single classed Warlock. Not to 20th level mind you, but to level 12. As such, I feel that I can finally come back and give a proper look at the warlock, and what I feel its weaknesses are, and how they could be shored up.
Do note, the DM did not hand out short rests like cookies. You could not do something like wake up, cast Hex, and then short rest immediately afterward before we actually did any sort of adventuring. Nor could you short rest after every fight. The DM felt that made things unbalanced towards the Short Rest classes...and I fully agree with him.
Spoiler: The Good
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They have such an amazing flavor, I absolutely adore it. The RP potential is huge, and fun. The fact that my spells scaled in level was really nice too, making even my "low" level spells count well past the point I thought they would. I personally went Hexblade, which was really fun, especially since my DM was a bit stingy on magic items. I ended up being one of the few players who consistently had a magical weapon, and Eldritch Blast made for a fine cantrip that ended up having a decent amount of utility.
The Invocations were fun too, in particular Mask of Any Faces and Eyes of the Rune Keeper were particularly useful and fun. Improved Pact Weapon, Agonizing Blast, and Repelling Blast helped keep me useful in combat too, even when I only had my cantrips available. Also, the Hexblade's abilities meshed really well with Pact of the Blade, and the Hexblade's Curse was especially nice. The Specter was useful, but its use eventually began to lessen the higher level we got. But that was to be expected. And finally, while I didn't get to play with it much, Armor of Hexes was also useful
Spoiler: The Bad
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Despite all of that fun stuff, I found the Warlock lacked one very important thing...Resources. I don't mean resources per adventuring day either. I mean resources in general. I found I never had enough spell slots per encounter, never had enough cantrips, never had enough invocations, and I never had enough spells that scaled well or worked well with the Warlock mechanics. Don't get me wrong, there were some fine gems in the Invocation department...too many in fact. I didn't have enough Invocations to really make something extraordinary, outside of Mask of Many Faces and Eyes of the Rune Keeper. Not to mention many of the invocations only come back on a long rest...which kind of ruins the point of playing a class that only uses short rests.
Hell, I had to rely solely on Booming Blade and Eldritch Blast once I reached level 5, since I didn't have enough Invocations to gain an Extra Attack without giving up one of my more useful Invocations. I wasn't really able to patch much with normal spells either, since the warlock has very few spells that scale well with his increased spell level slots. And because I only had a max of two spell slots per encounter for the majority of my play time, and only one spell I could concentrate on, I couldn't really afford to waste a slot on something that might not work. Generally I found I'd get to cast one potentially useful spell, and if it failed I'd be stuck with Hex for the rest of the time so that I'd have something useful at the very least.
To make it worse, there are very few spells that the warlock gets that can make use of their higher spell slots. Spells like Hex and Armor of Agathys are great, they scale nicely with the warlock and can be used for more then one encounter...but most spells don't do that. Either they're a one time use, they last one minute and have a chance to be wasted if the target makes the save, or they require concentration. Their spell choice and design does not work well with the warlock at all. The Warlock would have been far better if they had more access to spells that last multiple encounters a day and do not require concentration, like Aid, Armor of Agathys, ect.
Spoiler: Conclusion
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The warlock was somewhat fun to play. It was nice to step out of my comfort zone and play a single classed character for once, and nice to play the warolck. I loved their pact flavor, and was able to customize my pact in a way that allowed the DM to make use of it. It made for a fun, quirky character who could do some entertaining things. However, my previous thoughts on the warlock stand. Warlocks lack the encounter-to-encounter resources needed to be a super fun and great class. Their lack of spell slots per encounter, the limited number of invocations you gain, the low number of cantrips, and the low number of spells that really work well with the Warlock's gimmick hamstring the class as a whole.
That's not to say it isn't fun. It is a ton of fun...however I found that the roles I filled could have been filled far better with just about any other class. The only role I really excelled at was being able to read everything, and having a really great cantrip. Outside of that, I never had the resources to do much else.
Spoiler: Some potential fixes
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After having played the Warlock, I came up with a few ways that would make the Warlock be a bit more fun to play:
1) Give them one extra spell slot at 5th level. They can start out with one spell slot at level 1, have 2 slots at levels 2 through 4, then at level 5 they gain a 3rd spell slot. This alone would make it FAR better to play the Warlock, and gives players far more options during any encounter, instead of casting one spell and saving the second for Hex. Hell, Adventure's League doesn't mind giving Warlocks an extra spell slot at level 5, since Rod of the Pact Keeper is on the Evergreen Item List. For those who don't know, you now "purchase" magic items, and items on the Evergreen list are always available. The earliest you can gain a Rod of the Pact Keeper is right at the cusp of level 5, and it just so happens to be the only item that allows a caster to instantly regain one spell slot. It also gives a bonus to spell attack and spell DC...something very few items do. I find it indicative of the designers realizing they had made a mistake by limiting the Warlocks slots per encounter, and they tried to fix it with an item that boosts the number of slots a warlock can get, as well as the effectiveness of their spells.
2) Make it so Hex does not require Concentration. Making Hex non-concentration frees up so many things, you wouldn't believe it. It really does become one of those spells where you cast it at the start of the day, and just leave it running. It isn't OP by any means either. Hex only scales with how long it lasts, as it should. The damage and disadvantage to ability checks doesn't change. With it, you can do some actual fun things, rather then casting one concentration spell in an encounter, then getting to choose between Hex, a spell that's guaranteed to work and be useful, or some other concentration spell when the spell you're currently using ends. You actually get a choice for these things!!
3) Make more warlock specific spells that scale better. I cannot properly express how many Warlock spells either do not scale, or scale so poorly that there's no point in taking them. For example, Armor of Agathys, starts out cent, with the 5 temp hp and 5 cold damage. And you know what, the second level scales nicely too. 10 temp hp for an hour as a non-concentration is nice...but it quickly falls off. Then there's Arms of Hadar, 2d6 necrotic in a 10ft radius around yourself. The rider is pretty decent, denying anyone who fails the save a reaction...but the damage only scales by 1d6 to a max of 6d6 at 5th level.
And you know what, I'd be ok with those spells scaling poorly were it not for the higher level spells. They're first level spells after all, I don't expect them to be amazing. But then you see Hunger of Hadar. This is the only Warlock exclusive 3rd level spell in the PHB and Xanathar's! Obviously this should be great, right? It's a 3rd level spell, that's when you get stuff like Fireball and Lightningbolt...but no. It creates magical darkness in a 20ft radius, difficult terrain, and deals 2d6 cold damage and possibly 2d6 acid damage. The acid damage is avoidable though, since if you make the dex save you take no damage. Now, I will admit the darkness and difficult terrain are nice...but the spell does not scale at all. The damage never increases, the duration never increases. You are better off ignoring the ONLY WARLOCK EXCLUSIVE 3rd level spell for something like Fear, Hypnotic Pattern, Fly, or whatever your pact gives you.
4) Give them one extra pact specific boon at level 3. This actually frees up a fair bit, as they gain their pact boon and gain something fun to go with the boon, while still getting to have enough room for a combat Invocation and RP invocation.
Finally, with all that said, a small word about short rests, cause I know this will come up. It always does when Warlocks come up. The DM did not allow us to Short Rest whenever we wanted, and for good reason. I was not the only short rest class in the party. We had a Moon Druid/Barbarian and a Champion Fighter. Now, I often see people say that Warlocks should "just cast a spell like Hex at the start of the day, then take a short rest before the adventuring starts as part of their morning routine". I find this is a poor fix, as you're essentially saying the Warlock needs two extra spell slots every day without actually giving the warlock two spells they can use.
Not only that, but what of other, stronger Short Rest classes. I ask you this: Do you feel a Moon Druid should be able to use both of their Wild Shapes to turn into an Elemental and immediately regain all of their Wild Shape uses back before an adventure even starts? At level 1 they can just become a giant bear that sticks with the party. they won't be as effective at RPing, but I doubt they'll mind. At level 10, they can burn both Wild Shapes to be an Elemental. They aren't exactly hindered by this either in an RP sense like they are with the bear. Elementals can speak, which means a Moon Druid can use the languages they know to speak while Wild Shaped.