Well in the Baulders gate game if a warlocks patron dies then the warlocks Pact is revoked, in Wylls case with dyre consquences, but I can't find it in any of the books and no definitve proof online, anytime I have seen it in a campaign the character either dies or loses power based on the terms that held the pact.

Quote from MistWalker97 >>

Well in the Baulders gate game if a warlocks patron dies then the warlocks Pact is revoked, in Wylls case with dyre consquences, but I can't find it in any of the books and no definitve proof online, anytime I have seen it in a campaign the character either dies or loses power based on the terms that held the pact.

 Yeah the most common interpretation is basically that a warlock channels power from the patron like a cleric does a deity. Like a little judaism of one your pact is like the covenant in the old testimate where you agree to follow rules in return for semi-divine protection. 

I'm not a fan of that outcome personally because most of the fun of being a warlock is in trying to get one up on the patron. Having an ironclad contract that dooms you no matter what puts dampener on that.

Ultimately though this is not how a warlock has to work and it's kind of the least interesting one.

• Warlock characters like John Constantine basically trade for magical artifacts or abilities to boost their power like a demon created sorcerer.
• Others trade for magical secrets like basically every deal with Hermaeus Mora. 
  
  

For me, the patron has UNLOCKED the warlock's potential. It cannot be UN-unlocked. 

The progression continues regardless of the patron's desires. Hell, that's how you can piss off the patron who might send people after you for whatever reason. 

Now, assuming the patron's death at the hands of the PC? 

There's only one consequence that makes sense: would've warlocks start begging the PC to be their patron -- all the most whiny, self-entitled, crybabies. lol I would have so much fun with that. 

I would always focus on making this somethign the player can make decisions about, to ensure they have agency - even if the choices aren't necessarily their first. I'd avoid "you lose your powers" because to keep the game fun they'd have to level up as something else, which makes no sense.

One good example is the idea of them being cursed, which for a human might mean becoming a tiefling, for example. 

Another might be that their powers become a little unstable. They can still use them, but until they find another patron to help manage their abilities, they roll for wild magic surges.

I'd consider the idea of not allowing them to take further levels in warlock without a new patron, but only if it fit the story beats. I would avoid it if there's no good opportunity for them to pick one before their next level up, and handwave it as the power being already unlocked before and now they have learnt how to use it.

Definitely have potential new patrons try to win them over. Really go all-out - lavish gifts, opportunities for advancement, company carriage. Especially if you pick gifts they will genuinely feel qualms about turning down, and write in big consequences for the plot from their decision. The rest of the party will be egging them on to accept the awesome flaming carriage pulled by nightmares from the grinning skull that wants to take over their patronage, not realising that you have descent into Avernus lined up if they accept.