I have an idea for a magic sword that I want to introduce in my campaign, but I'm not sure if it's overpowered or underwhelming. It's a +2 semi-sentient longsword that gets sharper and more eager to cause harm the more it gets used. I'm thinking about representing this as it starts out doing 1D4 damage, but it's damage would go up by one die step every round that the wielder made a successful attack with it (1D4 to 1D6 and so on). If more than three rounds go by without the wielder making a successful attack, or if the wielder fails their attack roll, the sword goes back to doing it's original damage, and they have to start all over again.
Is this item a good idea, a bad idea, or does it just need some work?
The furyborn enchantment is circumstantially more powerful than the one described by the original poster.
I view the one described by the original poster as generally not OP or underwhelming. However, in the hands of a vital strike build and without a cap on damage dice, in a longer combat the weapon could get ridiculous.
That's essentially the idea behind the weapon. In a short fight, it wouldn't do too well, but in a prolonged battle or against a massive horde, it would really shine.
Sounds good with the modifications. Note that monsters at higher levels last longer because of better AC and hit points. You have to stack up those to hit modifiers to make use of it.
The sword wants their fighter to have that belt of giant strength.
That's essentially the idea behind the weapon. In a short fight, it wouldn't do too well, but in a prolonged battle or against a massive horde, it would really shine.
Except it wouldn't, not with "if the wielder fails their attack roll, the sword goes back to doing it's original damage, and they have to start all over again". If you are fighting any sort of quality opponent you are going to miss, even if you are using a vital strike build. And you'll miss often if you are using a more normal full-attack build.
It sound familiar, isn't there a feat or class ability or something (other than Furyborn) that does something similar?
Potentiality OP..A decent character builder will make a guy that can hit consistently a couple times a round at low level. So R1:1d4/1d6, R2 1d8/2d6, R3+ no balance....add in Lead Blades or Enlarge and it gets worse faster. Then think about the guy with Combat Reflex or Vengeful Strikes, they have full bab off round attacks. There is a reason Furyborn has a cap, for a +2 Effect it can only get +4/+4 Better at best. Your concept if great, but the application is too powerful in the right players hands. Maybe cap at 3d6 for a 1hander or 4d6 for a 2hander, both higher than most weapons maximum to offset the crappy d4 or d6 base you would use. If not by round three even a lower level character that is built well will own the fights.
For balance sake, think of the same sword in the hand of the non maxed character that get one attack a round, with a limited BAB and not focused, he starts with a trash damage die and it will reset often. They would hate the weapon. So same group, different characters and one becomes a god, the other a chump.
Cap it, it can be a gross cap say 3d12 or whatever but cap it.
I say cap it at 6. That is 1 more than the normal sword bonus.
Heck I think having it reset after the first miss is to weak it should go down 1 step with a miss and up 1 step with a hit. And yeah probably cap it like the others are saying. It does make the weapon type seem kind of pointless. How about it start at the weapons base and go up by 1 type per hit but only increase it at most like 5 steps. Would be a decent plus ability maybe +3 or +4 equivalent.