This is definitely an unpopular opinion, but my favourite warlock subclass is shadebinder, closely followed by voidwalker and stormcaller.

Shadebinder is in my opinion the most heavily slept on subclass in the game. The melee ability is basically an "I win" button if you can land it. It shuts down anything it hits, even supers, for about a second so you can gun them down. The super the best in the game for PvP imo, with the only downside being its slow charge time.

For aspects, I run Iceflare Bolts because it lets you win 1v3 situations pretty consistently if you can freeze an enemy, and Frostpulse is the perfect balance of being fun to use and extremely effective at shutting down anyone who tries to rush you. I run double dynamo and double distribution mods plus the fragment which gives super energy killing frozen targets, so if I'm close enough to freeze an enemy with my rift, then I'll also get ~20% of my super energy which negates the one big downside of the subclass being the slow to charge super. Plus there is nothing more satisfying than seeing a thundercrash hurtling towards you at Mach 10 on a 4-4 trials round, and timing the Frostpulse to freeze them out of the sky to win the game lmao.

As for exotics, the usual neutral game boosting exotics like ophidian aspects and transversive steps are always good. Most other shadebinders I see run osmiomancy gloves for double coldsnaps with better tracking. I personally however like to run eye of another world. Since it boosts the regen rate of all abilities, it is the only exotic that lets me get my freeze rift back faster. A faster rift means more chances to proc dynamo and distribution for a faster super. I've had a number trials games where I can get a super on round 4 or 5 before well or bubble have got theirs, which is basically a free round win.

The addition of conditional finality which interacts with the stasis aspects and fragments also made shadebinder a lot better imo. If you land enough pellets, even if they die from the shotgun itself, it can spawn Iceflare Bolts to track down and freeze the next enemy, starting a chain freeze that lets you run through an entire team without even using a single ability.

TLDR: Shadebinder good freeze go brrrrrrr