Magic items are an incredibly iconic part of a campaign. Over the course of one, each player character will typically have at least one item that is associated to them. While it isn't always the most useful of items, it can be hard not to think of the item when thinking about the character even years after the end of a campaign. In my experience, one of the things that makes an item memorable is an element of risk. It could be a risk to try and get a more powerful outcome to happen, or it could be the threat of a bad outcome. I'll begin by looking at some properties that can be added to a magic item for this particular purpose.
When Does the Drawback Happen?
In the games I took part in a player typically has to perform a roll similar to a death saving throw when making use of an item like this. If they beat it (roll 10 or higher), everything is fine. If they don't, a drawback occurs. We nicknamed this a “drawback roll” and it only applied to specific magic items. You can of course scale the difficulty as you'd like. Some items may have a very rare chance as low as 1 out of 20. You can also make it specific to the item, however it can get hard to remember a whole slew of different DCs. However, such a problem is easily avoided if magic items are carefully handed out. You can also include a skill or attribute modifier on the roll as you would any other check. The circumstance can also modify things, especially if the item is sentient. The short version is there are a lot of ways to have fun with this idea and I saw these rolls played with a lot.
Format For Properties
I've been trying to mostly keep things system neutral and use D&D 5th edition for examples. For this reason, the first paragraph after italics will be an explanation of the intended draw back. After that, I'll provide a sample implementation for D&D 5th edition. In the case of multiple version, I provide alternates below. Naturally, damage can be adjusted. I won't bother to list those as alternates.
Your arrow quickly leaves your bow and hits the target square in the chest. He falls over with a twist and lies motionless on the ground. You feel slightly weaker compared to before your shot.
The idea behind this item is that there is a chance to take some damage after an attack. The idea is that there is added risk with such an item. It's usually intended for a weapon, but also works well with a staff or other magical item. The damage taken typically should reflect the strength of the effect caused by the item.
Example Implementation: After an option is chosen, perform the drawback roll. In the event of a failure, roll 1d6 multiplied by the strength of the effect. The damage can be high to make it risky to use or low to allow repeated use by high level characters but also careful use by low-level characters.
Alt 1: Instead of taking damage, the user gains a level of exhaustion.
Alt 2: Instead of taking damage, the user can only take an action or move action until the end of their next turn (can be moved to 1d4 instead for more punishment).
Your arcane power is focused through your staff. Released in the form of a pitch black sphere, it flies ahead and explodes on impact. Shadows, acting like black fire, engulf all that are caught in it's blast.
The idea behind this trait is linked to a magic item I saw in use. The item was a staff that allowed the necromancer that was attuned to it to channel any spell through it. Doing so allowed them to change the type of damage dealt by the spell to necrotic. It also let them try to enhance its power.
Example Implementation: The object has 10 charges. 1-5 can be used at a time. Each charge adds 1d6 damage to the spell channeled through the staff. After an option is chosen, perform the drawback roll. In the event of a failure, the user of the object takes damage equal to the bonus damage.
As you try to activate its ability, the snakes engraved on the item seem to come alive!
The idea behind this item is that using it has a chance of failure. This unreliability makes using it a risk. Here is also an alternate version where later actions take a penalty. In game wise it can also be described as a defect in the item itself.
Example Implementation: When attempting to use the object, perform a drawback roll. In the event of a failure, nothing happens.
Alt 1: Enemies have advantage against the user and the character using the item has disadvantage on saves.
Alt 2: The user has disadvantage on checks/attacks and enemies have advantage on saves imposed by the character using the item until the end of their next turn.
The item erupts in brilliant bright light and warmth. You still see glowing white even after the warmth subsides.
This drawback was originally belonging to a sword that could erupt in bright like, sort of like a sun blade. However, it also blinded people for some length of time. The user and their allies were also not immune to this effect. There was also another sword but instead it blinded the user when trying to use it's power.
You will need to set a DC for enemies to resist the effect. Typically the user did a drawback roll instead in order to give them a better chance to resist. Characters who knew it was coming could try to cover their eyes.It's up to you if you want the item to affect party members or if the wielder has some level of control as long as they succeeded on their drawback roll.
Example Implementation: When attempting to use the the property, perform a drawback roll. In the event of a failure, you are blinded until the end of your next turn.
Alt 1: When attempting to use a property, perform a drawback roll. In the event of a failure, you are blinded for 1d4 turns.
All sound, ins a single moment, fades away.
The point of this drawback was to decrease perception and increase chances of walking into ambushed but also served to force the user to depend on their party members.
Example Implementation: When attempting to use a property, perform a drawback roll. In the event of a failure, you are deafened for one hour. Think of interesting ways this would effect role-playing.
Alt 1: You are deafened for 1 turn instead.
A single moment later, you can no longer hear your friend speaking. The chirping of crickets can still be heard in the distance.
Legend has it that it belonged to a thief and a mage hunter over the years. Who it was originally meant for is a mystery lost to time.
Having an easy way to cast silence is a useful thing for anyone who wants to sneak around or fight wizards. However, it can also be a downside to your own in close quarters. This item originally had 2 properties. One was to use silence as normal, or a slightly modified version of the silence spell. The other had a chance to activate it unintentionally as well. This works best on a player who has a conscience and feels bad for making their party spellcasters suffer. Also if they cast spells. The other time I saw it was on a magic staff. Made things rather tough.
Example Implementation: When attempting to use a property, perform a drawback roll. In the event of a failure, silence is cast centred on the item until the end of your next turn.
You feel a cold chill run down your spine as the world fades away. Darkness surrounds you from every direction.
The intention of this item was shadow magic. The drawback could also be an advantage in certain situations and the player used it to survive blasts that otherwise would have killed them. In this case, they could never use the property directly.
Example Implementation: When attempting to use the the property, perform a drawback roll. In the event of a failure, they are trapped in a shadow realm until the end of their next turn (similar to a forced ethereal form).