Do summoned creatures, such as with Summon Lesser Demons, give experience points to the party?

Question

I've looked at various conversations on here, Reddit, and other forums, but I can't seem to find any official ruling on this topic, so I figured I'd ask here and see if anyone knows of any.

There are other summoning spells, but in this instance I'm specifically referring to the Xanathar's Guide To Everything spell Summon Lesser Demons. The demons are not under the caster's control, have their own initiative and attack any non-demon in reach until they are either killed or the spell ends/is ended.

As an example, in our last session the wizard summoned 4 dretches to help in combat. One of the enemies killed one of the dretches, then, with no other enemies left, the party attacked the dretches, killing 2 of them. The wizard then ended the spell, getting rid of the fourth. Should the party be awarded for killing those 2 dretches?

RAW, it seems that if it's not a creature under your control that will attack you and the spell doesn't say anything to the contrary, they should be awarded XP for killing them. Of course, this immediately led to the party joking about XP farming. It'd have diminishing returns, but is still a loophole that I'd rather not leave open. (I know, DM fiat, I'm just wondering if there is any RAW or even RAI that would prevent it without me making a 'house rule' ruling on it.)

Answer 1

There's no rule that says that a creature that was summoned shouldn't count for the purposes of calculating XP.

The Dungeon Master's Guide does advise that if a challenge was trivialized through some unforeseen mechanism, then the party doesn't need to receive the full XP value of the enemies they defeated. So for example, if the party is up against 15 bandits, and they summon a group of demons to fight the bandits, then fight the leftover demons, it probably doesn't make sense to award XP for the demons or bandits that were slain in the Bandit↔Demon fighting, although it would probably still be appropriate to award XP for the remaining Bandits or Demons. If that seems unfair, I would also add that as a principle, if an entire encounter can be ended by a single spell slot, it probably qualifies as "trivially easy".

Conversely, if a party summons a group of Demons with a spell, and then defeats them, I can't think of an especially good reason why that shouldn't yield XP, except that such a fight would be unlikely to be terribly difficult to begin with, which again directs back to the "don't give XP for fights that are trivially easy" principle.

So you'll have to gauge on a case-by-case basis, but in general, one of two things are going to happen: either the party is regularly putting themselves in nail-bitingly difficult fights (and XP rewards are probably appropriate) or they're farming easy encounters and really shouldn't be receiving XP at all.

Alternatively, you could do what I do, and not use XP at all, as described in the Dungeon Master's Guide:

You can do away with experience points entirely and control the rate of character advancement. Advance characters based on how many sessions they play, or when they accomplish significant story goals in the campaign. In either case, you tell the players when their characters gain a level.

This method of level advancement can be particularly helpful if your campaign doesn't include much combat, or includes so much combat that tracking XP becomes tiresome.

—Level Advancement without XP, Dungeon Master's Guide, pg. 261

The main benefit here is that it breaks any kind of "XP Farming" players might otherwise be inclined to do. It also reduces bookkeeping for both players and DMs, and gives a bit more flexibility in the kinds of stories you want to tell, instead of having to constantly justify meat-grinder combat sessions, or otherwise derive appropriate XP values for the session where the party spent an entire session reenacting a scene from Phoenix Wright and never actually got into a combat session with anyone.