Give them chances to do research
As the group tracks down the villain, they might find traces of his spell research, or NPCs he has persuaded to help him create this fearsome spell. They might find his notes or even an old spellbook. Investigating these objects might reveal that the villain has this spell, and the proper way to counter it.
But honestly ...
This is somewhat more specific to your question about murder then some of the other (excellent) answer, but I feel the need to point out this rather simple solution to the "murder" question.
Ressurection and equivalent spells all say:
If its soul is free and willing, the target returns to life with all its hit points.
This might depend somewhat ...
I realise that I'm very late in replying to this question, but I think there's a key assumption in there (which was accepted by all the answerers so far) that isn't sound.
I don't believe that Modify Memory would suffice to erase the trauma.
Let's look at some quotes from the original post.
I pointed out that the trauma would still be criminal, and he ...
This is something I've struggled with as well, especially with Rifts.
If the campaign is focused on a particular region, such as Chi-Town or New West, I provide the players with key information. For this, I use a resource such as Obsidian Portal or World Anvil to provide the players with information on the area, notable people, etc... Stuff their characters ...
A very simple solution would be that using it drains his stamina very quickly. It is a powerfull weapon, but if he is not strong enough, he will be exhausted and get growing malus after eg: 5 turns and then fall asleep after 10 if he continues.
I'm all for providing a temporary NPC.
Ask the player to think of a short paragraph of how has the character's life and death affected the world. And write it down on the character sheet which goes to the archive of dead characters.
Hand the player one of 4-5 drop-in mini antagonists you have prepared. The card should hold sections combat stats, major ...
Use it to build his relationship with the Deity
The sword can be some holy relic with great powers. However the power is directly related to how close your paladin is to their god.
I did a similar thing (though with an amulet) where the paladin was awarded certain bonuses for different religiously motivated actions.
Minor actions such as spending time ...
Not a bad reason, as long as you take advantage of the opportunity you created
The god he follows is illegal in that world, so I thought it would be cool if the shopkeep had one,
This is not a bad reason to get a magic item, it is a great one! Tying the acquisition of a magic item into the background plot of your campaign deepens it in a way ...
Welcome to the wonderful world of "winging it"
It's an old DM/referee mode that's been around since before D&D was published.
Your reason wasn't a bad one
A common magic item costing 60 GP is within DMG and Xanathar's Guide to Everything (XGtE) cost bounds for common magic items. (It looks like the paladin was offered something like a 'friends ...
Make the sword scale with the user's power.
Since you haven't told the player anything about the sword's powers, I recommend that you homebrew a magic item that scales with the user's power; this could be, for example, their level, their proficiency bonus or one of their secondary ability scores (which would be CHA for a paladin; see PHB p. 83 "Strength ...
You haven’t specified what the item is, or even whether it’s a standard item or a homebrew. I would fiat that the character cannot use the item to its fullest without being of a sufficiently high level - that is, a low-level character can only use a few of the abilities of the item, but as the character gains levels, more abilities become available. This ...
Make it a quest
There are lots of ways to deal with this, but my favorite way is to turn this into a quest. There are a few ways to do this:
When he tries to use the sword, he's unable to and realizes he needs some other item / special spell / password to fully obtain its power.
The sword is stolen during the night by a shadowy enemy who wishes to use its ...
They should go through character creation as normal, though either of your first two bullet points will be fine
I've never run a Hunter game, but have a fair bit of experience with Vampire: the Masquerade which is relevant to this issue. My textual support, specific to preludes, is the prelude section of the VtM 20th Anniversary core rulebook (pages 352-354)....
This is a game system breaker, but It will reduce the time per round alot.
First, change player AC from a set amount to varied amount. To do this, a player takes their AC and minus 10 from it to become the AC modifier. Then you would use a D20 roll to add to the AC modifier. \ Monsters will change their attacks from varied to static. To do this just add 10 ...
Wow, a hot question. My solution follows, although I do not claim this is The Solution.
Make up a simpler system. That applies only to
NPC to NPC interaction
too many NPCs fighting too the PCs
wtf moments for the GM
The system is:
for any decision( attack, skill, luck ), throw 1d6
1 means "worst possible", 6 means "best possible"