I've been reading my way through the DMG, and naturally, I started with the treasure and magic items because there weren't any monsters to start with. Many of the items require attunement, which is covered in the 5e DMG, pages 136-138 (actually, 137 is all tables, so it's just a few paragraphs spread over 136 and 138) and p. 285. Basically, you spend a short rest with your new, powerful magic item and attune to it before you can use it. Not all magic items need this, and you're capped to three.
Ken Harrison switched his existing Monteport game to 5e, and implemented attunement, triggers posts about it from Douglas Cole and Tim Shorts. I jumped in with comments. What I mentioned over on Gaming Ballistic is that attunement basically is a tradeoff between curbing abuse and curbing the awesome.
Abuse - turning a magic item into a magical problem solver for everyone, or the stacked effect effect. The ugly side of allowing immediate and full use of any item is clear - everyone dons the Efreeti Mail to walk through the fire trap one by one. The Ring of Regeneration is passed around from person to person to heal them up. Using the Boots of Striding and Springing to get everyone up that cliff and then toss them down to the next person. That kind of stuff.
The stacking abuse is the "two Rings of Protection +3 and a Cloak of Protection +3, for +9 AC and +9 on Saves!" kind of thing. Or wearing Elven Mail +3 under Plate +2 and claiming a +5 bonus.
"Awesome" is basically when passing around magic items or accumulating them does cool things. The last man standing gathering up his friend's Sword of Sharpness and continuing the fight. Putting the Ring of Warmth on someone freezing to save them. Finding and donning that ring you found in the darkness and finding out it's a Ring of Invisiblity and works right away.
It's also stacking up everyone's Rings of Protection on the guy challenging the enemy champion one-on-one or opening the trapped chest, or buffing up the wizard before he teleports someone risky and dangerous, and otherwise taking the resource that is magic items and focusing it in one place to do something otherwise impossible or impossibly risky.
So attunement needs to walk a line between curbing abuse ("Don't Bogart that magic ring, dude!") and curbing awesome ("Take my sword . . . and have a short rest so you can attune to it . . . and keep after those orcs who kidnapped the princess!") Ultimately, though, it's only there because of the wish to curb abuse. It's not there to make things more awesome, at least not as written. As Tim said, I cuddle with my new item for a while and now I can use it . . . doesn't sing a song of the sagas to me, anyway.
What I've done in my own games is similar, so I can't just point at attunement and say "Bad Wrong Fun!" or even "Bad Rule!"
For certain items, especially those with potentially abusive effects, I tend to put a delay on them. Ring of Regeneration? Wear it for 1d hours (or even 1d days) before it starts to actually work. Or, alternatively, the effects ramp up (First nothing, then Rapid Healing, then Very Rapid Healing, then renegeration starts.)
This sort of approach works best when the effects are either very great, and abuse by passing it around are especially worrisome. Or, if thematically an item should just not work until you've fiddled around with it.
For specific types of items, you can restrict the number of attuned items and still be very, very GURPS-like. Look at Powerstones (standard GURPS Magic) vs. Power Items (GURPS Dungeon Fantasy). The first is restricted only by recharging interference, as stones close than about 6' apart will suppress the recharging of lesser sized stones . . . but you can tote around as many as you can afford. The second is a single item, period, so no caster can have more than one, and trading up is better than accumulating more. In fact, the single item is so ingrained into the game that some races pay for a perk to have better (more powerful) Power Items.
You can even go as far as charging character points. In other words, don't make an item a power grant, make it an excuse to buy a power at a discount. Find the Ring of Dark Vision, and you can buy Dark Vision with a discount for being gadget-based. That's a bit more super hero game like, though, in that magic items in supers games tend to stick around forever with that character, which isn't the case in fantasy so much. You can extend the idea, though, and charge some kind of meta-game currency (character points, points for Impulse Buys, uses of Luck, temporary disadvantages, etc.) to those who want the item to work. Then it's not something you can pass around ("Okay, pass around the Helm of Telepathy. We all pass the mind-lord's telepathy test and win the prize, and we all have Migraines for a week from adjusting to it.")
What are some alternatives?
Douglas Cole posted a series of good potential alternatives over on his blog. Here are a few I like:
- Allow both attuned and non-attuned usage. Splitting the effects you can access makes sense - anyone mage can pick up a Staff of the Magi and go to town with its basic Flaming Sphere spell (or Fireball, in GURPS), say, but you must study it and unlock its secrets and/or master it (Quick Contest of Will, don't lose! - or maybe a Content of Will for a really tough item) before it does much else. A Ring of Regeneration might give only slightly improved healing until you attune to it.
- Ditch it. It's not like attunement is so central to D&D5e that you can't just get rid of it. Come up with some alternate rules about stacking effects, limits on the number of like items (one magic ring per hand!), and don't worry about abuse. Ken did this, ultimately.
- Limit it. Keep it, but limit the items that need it to a rare, abuseable few. I keep bringing the Ring of Regeneration because it's so easy to abuse.
- Expand it. Keep it, expand it, but allow more attunement. Basically make the problem smaller by making it a feature of all permanent/charged magical items and then increasing the number of covered items.
If you look at attunement solely as a game-balancing rule, it gives you a little perspective on how to use it. It will also affect the world - a world where you can pass around magic items to gain their effects immediately is different from one where you need to attune to them and are limited in the amount of such. Making a decision about attunement seems more like a campaign switch than a rules balance concern. All in all, I approve of Ken's decision to ultimately chuck it, but it's a good example of a rule that can have subtle or not so subtle effects on the game and the world the game takes place in.