Requesting Insight on a Custom Item [3.5]

[RogueDM]

I run a predominately (with some house rules) 3.5 campaign and had an idea for a custom magic item with some atypical rules. I was hoping for peoples' opinions on flavor, balance, and overall mechanics.

The item appears to be a standard piece of jewelry (an amulet or ring), and upon touching it the wearer feels great confidence in whatever they're currently doing. This feeling returns each time they touch/activate the item.

The Good Stuff: Activating this item confers a substantial bonus to the next d20 roll. My instinct is to say a +20 to the next d20 roll.

The Down Side: Unbeknownst to the player is that the item has a set number of charges and as soon as the item is fully discharged -or- abandoned the wearer suffers a curse. Receiving "random" (read as DM's discretion) -20s to d20 rolls equaling the number of times the item was used.

Synopsis: It allows you to front load good luck in exchange for equal amounts of bad luck later.

Concern: This could potentially make one member of a party more than slightly OP for a while, side-lining other party members. Secondly, the Down Side could easily become a joy-kill for the cursed character's player.

Acknowledgement: To keep these effects secret from the players one may have to conceal the Down Side from spells like "Identify". I believe there are non-cheese/non-Rule Zero methods of doing this but I can't think of them off-hand.

Acknowledgement 2: Wasn't sure if this properly belonged in Homebrew or 3.5, but this seemed more appropriate.

[Djinn_in_Tonic]

I'd be really careful to hand this out. The potential is there for the -20 penalty to serious destroy a character if used at important times, or really not actually be that big a hindrance if used an unimportant times.

Meanwhile, the +20 bonus to rolls are a little insane, and will be used at times when it really matters.

It just feels way to swingy. I think you'd be better off with a smaller bonus/penalty...say, +5.

[RogueDM]

I'd be really careful to hand this out. The potential is there for the -20 penalty to serious destroy a character if used at important times, or really not actually be that big a hindrance if used an unimportant times.

Meanwhile, the +20 bonus to rolls are a little insane, and will be used at times when it really matters.

It just feels way to swingy. I think you'd be better off with a smaller bonus/penalty...say, +5.

Fair point. A -5 should still be enough for a player to realize that he's suddenly hit a preternatural run of bad luck.