Shadowhexer

[ChudoJogurt]

I believe it is the current consensus that both Hexblade and Shadowcaster are Tier 4 classes.
Would Gestalting them together make a decent Tier 3 class?

That way the the Hexblade chassis compensates for the lack of uses-per-day on the Shadowcaster, allowing them to go into melee competently at lower level, and in addition most of Shadowcaster Mysteries are actually quite conductive to a Gish build.
Fluff-wise, the flavour of Hexblade as darker counterpart to Duskblade seems to work pretty well with Shadowcaster.

Has anyone tried that?
How do you think this would work?

[EndlessKng]

I believe it is the current consensus that both Hexblade and Shadowcaster are Tier 4 classes.
Would Gestalting them together make a decent Tier 3 class?

That way the the Hexblade chassis compensates for the lack of uses-per-day on the Shadowcaster, allowing them to go into melee competently at lower level, and in addition most of Shadowcaster Mysteries are actually quite conductive to a Gish build.
Fluff-wise, the flavour of Hexblade as darker counterpart to Duskblade seems to work pretty well with Shadowcaster.

Has anyone tried that?
How do you think this would work?

Never tried it, but it seems likely to not work super well.

The biggest issue is that, without changing anything about either class, it is MAD as hell. Hexblades are intended to be Gish, which means they already need a lot of traits for combat and spellcraft. At least, you need Charisma for spells, Strength for melee, and constitution for hitpoints. You probably want some Dex for AC since they don't get the ability to cast in Armor without Penalty. Meanwhile, Shadowcasters need Intelligence for casting. Even if you emphasize the Shadowcasting side to get the Int 19 you need to use 9th level effects, you would need an Charisma of 14 to get all the Hexblade spells. And if you keep that Charisma low, the spell and Hexblade Curse DCs will be low enough for mid-high rank enemies to get out of easily.

Also, you're expanding your casting options, but to a limited extent. Hexblades have known spells on a spontaneous basis; shadowcasters use each mystery a set number of times each day, IIRC. It's not like a wizard who can prepare three fireballs one day and then three different spells the next; each mystery can be used a certain number of times. So, your mystery choice defines a lot about your capabilities. This will leave you with tools that don't get used super often.

Now, the two do offer some benefits to each other. Hexblade has a couple useful passive buffs, like adding charisma to saving throws and gaining Evasion on Will and Fort checks. Their familiars are also tougher than usual. And Shadowcasters add a Fortitude Save to the Hexblade, making them more resilient still, and benefits from the added health for sure. Shadowcasters also get bonus casting-related feats, some of which could help the Hexblade And carefully chosen, I'm sure there are several mysteries that could help in melee combat. But you're still looking at making a MAD class even MADder, at least as written.

If your DM let you homebrew it, you could potentially change one casting stat to the other, depending either on Int or Cha rather than both. This isn't a perfect fix, since that just leaves four Attributes that need some attention, but it's better than five, and it'd be no worse than being a straight Hexblade. However, you may be better off just grabbing Warlock instead of Shadowcaster - you have fewer options still, but some of those options are flat broken (renewable invisibility, the shatter spell, and flight, all at will among them; also, glaivelocks are a thing and hexblades really work well gestalted to those designs).

This wouldn't necessarily be the worst gestalt I've seen, either in general or in the case of trying to bolster two lower-tier classes, but it feels like it doesn't solve all the fundamental issues at hand with both classes.

(Also, if you never saw it, look up Mike Mearls' hexblade fix suggestions here (look for the "When All Else Fails" section): https://1d4chan.org/wiki/Hexblade. It does some stuff that helps the Hexblade be more useful and solid on its own).

[ChudoJogurt]

I saw the semi-official errata for the Hexblade, but IMO it does not go far enough.

And yeah, perhaps I have not formulated the idea well enough -- Gestalt is not the right word.
What I meant was substituting Hexblade spells to Shadowcaster mystery progression, leaving the rest of the chassis as is. Perhaps, as you rightly noted, shifting casting stat for Mysteries to Charisma, so that it synergises better with Hexblade curse.

[Psyren]

Your other problem would be spell failure, though Still Mystery helps with that. As written, using that might make your spells full-round actions though.

But yeah, needing Str/Dex, Con, Int and Cha is a bit much, so you'd have to do more than simply smoosh the classes together.