I'm a bit fan of 'wording means everything' when it comes to the wish spell. If the statement is "Kill all of these things forever" Completely ignoring any complications with their ability to ignore magic or death or be immune to death for one reason or another, my thought is how are they going to be killed? Kill all the thing? Got it. War of the gods should do that. Kill all of the thing? Alright, time for some new of that thing to come into existence.  Kill all of the thing? Cool. That excludes all of these tangentially related things and that thing that are currently on other realms of reality like a demiplane. 

Quote from RianStormwind >>

Quote from XXXGammaRay >>

Quote from Leif_the_Red406 >>

would you as a DM allow a wish to "irrevokably kill every lich and demi lich on the continent of Faerun"? Or instead of 'continent' maybe "10 mile radius sphere centered on me"

It would be a quickway to simply not have to playout a difficult encounter the players knew was coming their way.

 

Depends on the DM and what the expectations were set forth during session zero.

For my table, I would just rule that specific Wish spell does nothing because liches are already dead.

 I would like to point out that death and undeath are two different states of being. Liches are undead, so they can be killed.

In the strictest sense of the word, killing something requires that something to be alive. The undead are not alive. They are not very different from constructs, and the primary difference is that the undead are usually made from animal matter whereas constructs are usually made from plant and/or inorganic matter, and both are brought to "life" through magical means and occasionally through scientific means. From how I see it, the undead are just as dead as golems, living spells, clockworks, and the dirt and rocks on the ground.

Quote from BioWizard >>

Quote from Leif_the_Red406 >>

would you as a DM allow a wish to "irrevokably kill every lich and demi lich on the continent of Faerun"? Or instead of 'continent' maybe "10 mile radius sphere centered on me"

It would be a quickway to simply not have to playout a difficult encounter the players knew was coming their way.

 

I can think of no way to word a wish that would successfully accomplish what you describe, which would be to remove all liches and demi-liches from the game, without having unintended consequences. For example, if you said, "I wish every lich and demi-lich in the world were permanently and irrevocably dead," that might get you time-shifted to the far distant future, when the sun is a Red Giant, and all living things on the surface of the world have been destroyed, including all liches. You got your wish -- there are no more liches. And you are now out of the campaign for good, since you exist in a time millions or billions of years in the campaign world's future. Or perhaps, there is some "god of liches" who considers them his "children" or servants or something, and after you killed them all, the lich-god, who is CR 100 or something, shows up and one-shots the entire party. Again, you got your wish, and now you are dead. There are any number of ways such a Wish could go wrong, and because the Wish is being made for metagame reasons as you describe it (the players know something is coming and want to remove the challenge the DM has set up), I would make absolutely sure that whatever happened as a result of that Wish, was so much more infinitely worse than just fighting the lich in the first place would have been.

As a player, one is responsible not to do something that breaks the world or the game, or ruins the game for other players (including the DM!). Taking every lich out of the world destroys thousands of possible plot devices for the rest of the campaign, hundreds of possible interesting enemies, and utterly wrecks the entire world in terms of lore and backstory for the rest of the time in which the table plays in that world. It doesn't just wreck it for this campaign, but it wrecks it for the DM ever setting anything else in that same world in the future, because all the liches are gone and any story about such creatures are also removed. You're not supposed to, as a player, purposely and knowingly wreck a thousand future storylines like that, for any reason. A Wish like this is a Wish made in bad faith by the player, and as a DM, I would try to warn the player off, but if they insisted, I would find every possible way to make it go bad, and make the player wish, that the character had never actually cast that Wish.

 Lich God is Vecna but I can see Orcus as a final boss. If your goal is just to rid the world of liches you just need Atropus the World Born Dead. From, Curse of Strahd? Tomb of Anhilation? One of those. It created an effect that consumes souls and souls cant be trapped any other way, it could pluck Lich souls out of the air before they make it back to their Phylactry. Might cause other problems but hey the fun of wish is the butterfly effect.

Quote from RianStormwind >>

Quote from XXXGammaRay >>

Quote from Leif_the_Red406 >>

would you as a DM allow a wish to "irrevokably kill every lich and demi lich on the continent of Faerun"? Or instead of 'continent' maybe "10 mile radius sphere centered on me"

It would be a quickway to simply not have to playout a difficult encounter the players knew was coming their way.

 

Depends on the DM and what the expectations were set forth during session zero.

For my table, I would just rule that specific Wish spell does nothing because liches are already dead.

 I would like to point out that death and undeath are two different states of being. Liches are undead, so they can be killed.

 Not quite most of the undead stat blocks refer to them being destroyed at 0 hp as if they are not creatures persay but fleshy constructs, this could be the DM loophole, grant the wish in a way definitly not intended. Liches the stat block, if counted as a creature, dont care if they die because they will reform in 1d10 days just as dead as before. You have to destroy their phylactry, or they come back from a state known as "dead", the lich is more an object that generates a human shaped weapon every 1d10 days its been without one.

Quote from ftl >>

So this seems like a weird wish, because it's simultaneously super-powerful and boring.

Generally I'd want to treat Wishes in kind of a yes-and manner - give the person what they wished for (no need to be a jerk and mess with it over wording, I'm not a fan of that) but make sure it has complications which set up some cool adventure to follow. But this "kill all liches" wish... like, why would the player even wish for that? Is there some specific lich they want dead? Do they just generally hate undead?  How is this wish interesting or useful?

It's way too much to ask for, because it's wishing for the destruction of a huge number of powerful spellcasters, many of whom are themselves capable of casting spells of this magnitude. It's not interesting, because it's not setting up some cool thing to do in the campaign... so it seems like it's up to the DM to make something cool out of this wish, because the player isn't.

So. What can be done here to salvage something campaign-worthy out of this trainwreck of a wish.

One option is just that the wish fails. I think that's a fine outcome here, because it's way too powerful of a request.

Other options... This particular quote makes me think the player is just trying to quick-win a particular encounter:

It would be a quickway to simply not have to playout a difficult encounter the players knew was coming their way.

 

Winning a specific encounter via the Wish spell doesn't seem like it's too much. They are, after all, risking a 33% chance that they'll never be able to cast Wish again. If they're trying ot murder a specific lich with this, I'd allow it - with the twist that the Lich's remaining forces manage to find and counterattack the party, leading them to have a fight where the wish-caster takes 1d10 necrotic damage per spell level they cast and has 3 str. Or maybe have the Wish spell instantly transport the party in to the Lich's inner sanctum as part of the "kill the lich" wish, thus making them fight their way out  of the lich lair while the wizard is in that state? ...yep, that's what I'd do here. If they're targeting a particular Lich with this, they instantly teleport to that Lich's location, and the lich dies, but then the party has been thrown, unprepared, into the middle of a dungeon, with their wizard being unable to cast leveled spells without taking 1d10 damage per spell level, and unable to walk on his own. ...though at this level, the party might have other spellcasters that can somehow trivialize the escape? Dunno. Make the escape a bit tougher than that somehow.

 

Alternatively, maybe they're trying to destroy the liches in general, because they hate undead so much. OK, sure, if this is a nice culmination of the character, maybe make this do something. Maybe the effect of this wish is that all current liches' transformation into liches is instantly and irrevocably undone - they turn back into their mortal pre-Lich selves, and cannot become Liches again. They are now mortal, and will all die within the next 10-50 years. They are, of course, all still the kind of powerful and evil spellcasters who really wanted to be liches, and now they have all been denied that. They are *definitely* going to be working on how to get revenge for this, and working on how to undo it! That could lead to some good followup adventures.

Anyway, yeah, I'd say it's up to the DM to read the room and figure out how to make this wish into something fun and not dumb. Though I'd definitely be giving the player some side-eye for even trying this.

 All liches die, they know who killed them and how. Each lich in the world rolls a d10 and comes back in that many days knowing who you are and what you did. "I know what you did last summer" new campaign for high level adventurers. This was helpful, gonna go work on 200+ Liches to hunt the party

Quote from Leif_the_Red406 >>

thanks XXX, you make two key points - word choice is critical with this spell, and speaking with the dm in also very important. If they are already dead why do they have about 135 HP?

 I mean a door isn’t alive