I am running a home brew 5e game. My group has recently levelled up to 2 and is about to come to the end of a dungeon. I rolled on the loot chart, and the results seemed quite generous for a party of that level.
Money and gems I'm not too worried about. Magic items were potion of clairvoyance, elixir of health, handy haversack, and beads of force. The beads of force ring alarm bells because they would probably kill any creature I could conceivably put up against them.
Is there a good rule for how many magic items/gold a PC should receive per level? Is there a limit to the value of any particular item the PCs have based on their level?
Best Answer
Xanathar's Guide to Everything has a section discussing this.
The section starts on page 135, and I won't reproduce it fully here, but I'll give a brief overview of what relates to your question.
The first thing is it notes a distinction that the Dungeon Master's Guide respects, but never actually explains directly:
Items found on tables A-E are considered "minor" items, while F-I are considered "major" items, regardless of their actual rarity.
Looking at the tables, it's clear that most of the minor items either have limited uses (potions, scrolls, dusts, and so on) or are what you might call "magical adventuring gear" rather than combat equipment. The few permanent combat items on the list are attractive only to certain classes or builds. (For example, Mithral Armor is on table B, but it's really only attractive to stealthy or physically weak characters.) All the stuff you usually think of as "magic items", like a +2 sword or a ring of invisibility, are major items.
It then gives a table with guidelines in terms of level ranges and how many items of each type you should be acquiring. It's only an approximation, of course; "should" is very much just a suggestion. If you're a little above or below, no big deal; it's just so you know if you're going way outside expectations, especially with major items or high-rarity minors.
By the way, there's a sidebar that notes that they expect you to make about 7 rolls on the "Levels 0-4" Treasure Hoard tables, so if you're at level 2 and this is their first haul of items, you might roll up a second hoard to add to the first one, and be cognizant that you'll be doing about 5 hoard rolls in the next couple of levels. About a third of your 0-4 hoard rolls will contain no magic items at all, another third should contain only "Table A" items (which is mostly healing potions and low end scrolls), and the remainder have all the good stuff.
Applying it to your situation:
The table says you should expect a group to acquire around 11 items between levels 1 and 4, with 6 common items, 2 uncommon minor items, 1 rare minor item, and 2 major uncommon items.
So if you're at 2nd level and this is their first big treasure hoard, you should probably have pulled about half of the 11 items in. So you should expect perhaps 3 common items (most likely expendables like potions of healing and such), 1-2 minor uncommons (or one minor rare), and one big centerpiece prize of a major uncommon (like gauntlets of ogre power or a +1 weapon).
Looking over the comment where you gave your specific rolls, I see you came up with four minor rares and no major items. While that's a lot of minor rares according to the XGtE charts, the specific rolls you got really aren't overpowering. The beads of force are definitely the exciting tool in this particular lot, and while they're good, they aren't too overpowering even for a low level party. But if you feel concerned, you could certainly replace all the beads with a single major uncommon item (I'd suggest one roll on table F).
Don't worry too much.
Generally speaking, it's fine if one hoard is a little on the generous side; you can keep that in mind as you roll for the next one. If it comes out a bit stingy, then everything's fine. If it comes out generous again, just nix one or two of the items. But the game tends to be designed pretty well so if they get more than they "should" have, they just have a slightly easier time for a couple levels, gain XP faster, and level back out again; and the more random treasure hoards you roll, the more it'll all average out.
Gold doesn't matter nearly as much, especially if you don't allow buying magic items. I wouldn't worry too much about it as long as the Magical Costco isn't available. Crafting takes a lot of downtime, so you're kinda in charge of how much of that they can get away with anyway, and PC-crafted major items should be the kind of job that kicks off a sidequest of its own -- "If you want to make gauntlets of ogre power, that's no problem; you just need the heart of an ogre, freshly killed. Shouldn't be a problem, right?"
You had expressed some specific concern about 2nd level characters having a set of beads of force, but they really shouldn't be a huge worry. 5d4 damage averages to 12.5, which is only slightly higher than the 10.5 of a baseline burning hands and deals no damage on a save -- and most Challenge 2 monsters have 30 or 40 HP. More importantly, a bead of force that deals damage also bubbles the target, which removes them from combat and stops the party from dealing them any more damage. You can't pound away at a big monster with multiple beads of force unless you want to wait a full minute each time for the bubble to pop.
If the party really wants to burn 3 to 5 beads of force with a minute wait between each to try to cheese through a boss fight, let 'em. They're spending a really good treasure (for their level) to do it, and that's not even the best use of the beads. (The best use is popping one on a horde of incoming enemies to hurt and bubble some of them and get them out of the fight, splitting up a big brawl into waves -- it's much easier to fight several waves of 3 orcs than one group of 9.)