how would you award XP to this party?

[irdeggman]

irdeggman: It's hard to explain, but what I am saying is: your individual XP per encounter is dependent on 2 things: your level, and the number of people in the party. What it does not depend on is the level of your other party members. Therefore, it's to your advantage, XP-wise, to have other party members who are higher level than you (since they will presumably help more and them simply being a higher level doesn't lower your total XP), and to your disadvantage to have other party members who are lower level (for the opposite reason - they're basically leeching without helping). (Of course, this is all rather meta and has nothing to do with why you might be partying with someone of a very different level.)

Actually in a way it does.

EL is based on the average party level.

So the levels of other members of the party determine what an appropriate challenge an encounter is. If there is a drastic difference then the challenge will end up too low to do the higher level PCs much good xp wise.

In your example 4 8th level PCs and 1 4th level NPC the average party level is = (4*8 + 1*4)/5 = 7.2, round down to 7. This is different then the 8 it would have been without the lower level character or if there were 5 8th level characters.

For a party of 5:

the xp for an 8th level character against a CR 8 = 480 (2400/5)
for a CR 7 = 420 (1400/5)

If the average party level is not factored in and appropriate adjustments to the EL are not made then very, very bad things can happen. Too high a CR (and very high PC mortality) or too low a CR (and essentially little challenge and less xp). {Nobody ever said the DM's job was easy }

 

[Jhaelen]

IMC, an npc accompanying the party only gets a share of the xp if he actually participates in the combat. So an npc who is more of a noncombatant and thus a liability won't negatively affect the party's xp.
Likewise a powerful npc will typically try to stay out of combat unless it looks like the party's in serious trouble. Only if he starts to intervene (or is targeted by an enemy and forced to defend himself) will he get a share.

 

[green slime]

Bah, the dude is an NPC... Just have him die at a suitably convenient place in the plot and be done with it.

 

[green slime]

The NPC's IMC joining the party, I treat like red shirts. They get to expose all the dangers, blunder into things, open the wrong box, and generally die in nasty ways, after the PC's have taken a liking to them, of course.

 

[eamon]

If the NPC is essentially a real party member, and XP is a means of communicating that to the party then just award him full XP - that is, the 8th level party members now get 20% of the nominal XP instead of 25%. That's not a significant reduction and won't really impact the PC's. However, the NPC will rise through levels fast. If that's not what you want, treat him instead as a cohort - he doesn't "cost" much (or any) XP, and is simply always 4 levels behind the party. That's easy, all right.

I only bother levelling NPC's if they'll likely return later and the PC will encounter them.

 

[evilbob]

Actually in a way it does.

What you said is technically correct, although even more meta than I was going. Also, not that it's particularly germane, but I'm actually running a module, so the encounters are more-or-less fixed.

Bah, the dude is an NPC... Just have him die at a suitably convenient place in the plot and be done with it.

"...a 4th level NPC that's pretty important to the story..."

...the 8th level party members now get 20% of the nominal XP instead of 25%. That's not a significant reduction...

You are right, but I guess I still see that as pretty significant. Certainly over a large number of encounters 5% can really add up. But you are right that it is not that big a deal in the scheme of things.

 

[irdeggman]

What you said is technically correct, although even more meta than I was going. Also, not that it's particularly germane, but I'm actually running a module, so the encounters are more-or-less fixed.

Then 1 of two things should be pressnt.

The "siginificant" NPC present is already accounted for (I think you alluded to the fact that he is part of the module)

or

the module gives advice for adjusting the encounters for higher or lower level parties.

If neither condition is present then you, as the DM, still have the right (and responsibility) to make said adjustments yourself.

Reducing or increasing the number of baddies per encounter is the easiest, throwing in another "random" encounter is another handy way to account and then there is adjusting the level of the BBEG (almost never recommended since having all of the EL tied into a single creature leads to all kinds of tricky things - like higher level creatures/characters with special resistances that a lower level party can't bypass due to lack of access to said spells, etc.)