The other day, while going through the DDI Compendium and Mordenkainen’s Magnificent Emporium, I realized that there were levels at which it would be impossible for a player to acquire certain magic items. Specifically, uncommon or rare magic items of a level equal to, or less than, the party’s level. By the rules as written, PCs can only purchase magic items that have a common rarity. Uncommon or rare items are available through treasure but only if they are between one and four levels higher than the current party level.
This is not a problem under most circumstances when it comes to weapons, armor, implements, or neck slot items, as these item types have new versions every five levels. By the time a party reaches a level that they couldn’t get a +1 version, a +2 version is possible to acquire through treasure. However, even in this case, the party would not be able to acquire an uncommon or rare magic weapon equal to their level. Magic items equal to their level won’t show up in treasure, yet the next higher ‘plus’ is five levels higher, and thus too high to get in treasure.
This becomes even more problematic for items like dragonshard augments, rings and wonderous items some of which are available every 10 levels, some of which are only available at one level.
It’s not as if lower level items are of such a low utility that they’re not worth getting, but you definitely don’t want to break the rarity system by allowing the PCs to purchase uncommon or rare items of lower levels without restriction.
Here are a couple of options:
1. Allow the PCs to purchase single uncommon or rare items of their level or lower.
I don’t particularly recommend this option as it does wreck the feeling that uncommon or rare items are ‘special’ and they become a source of optimization again, even though they’d only be available as single items.
Also, it damages the verisimilitude of the setting. A reasonable question would be why these items would become available only when the PCs gain a certain level?
2. You can simply replace a Level + 1 magic item with one or more magic items of lower level, according to the following:
One Level + 1 item = One Level + 0 item
Two Level - 1 items
Three Level - 2 items
Four Level - 3 items
Five Level - 4 items
and so on. If you are replacing an Uncommon item with lower level Rare items, halve the amount.
I would recommend not converting magic items more than one level higher than the party’s level, as I feel that reduces the ‘coolness’ of getting those items in treasure.
As for magic items five levels lower than the party’s level, or lower, it’s probably not worth worrying too much about it. If it’s cool, put it in the treasure parcel.
All this being said, I wouldn’t do this too often. More magic items, even of lower levels, will impact the power of the PCs somewhat, and certainly will increase the complexity of decision making. If you’re going to add lower level magic items to treasure, add ones that are cool or simple.