We've all been there. You take your BAMF vampire/necromancer/husk/all of the above out for a spin in adventure mode, and you come across a particularly gnarly historical figure with a great many kills to his/her/its name, eager to reduce you to nothing more than another name on a list I'm about to go off on. You're quite gangster yourself, and honor dictates that only one bad dude can survive the ordeal, resulting in a battle the world will remember for all time.
As you do battle against this worthy foe, he/she/it makes certain to remind you of all those who came before you and fell like so much wheat before the harvest.
Over, and over, and over, and over, and over, and over again.
It gets repetitive, it gets old, it gets boring. What should be a clash between living legends becomes a crawling ordeal repeatedly interrupted by a long list of people who lost the not-dying contest, which you have no choice but to sit through before getting back to the action. It would be like if a boss battle of any other game was interrupted by a cutscene every time you landed a hit.
Anyone who's played adventure mode long enough has dealt with it at some point. Some opponents are better about it than others, almost never mentioning their kills, while some will rattle off their list every single turn, dragging out the ordeal for much longer than it needs to go on. It can wear on the nerves after awhile and subtract form the experience, but I will admit, it is a very strong motivator to kill the offending creature.
So how best to deal with this issue? You could include the option to remove kill bragging entirely. More options is good options, but there are better and more subtle ways of handling this.
I do think creatures that cannot speak should not have any ability to brag about their kills. If the creature cannot speak, it has no way of conveying that it has killed other creatures, and whoever it would convey this message to should have no knowledge of the creature's history unless learned from elsewhere, such as hearsay from the inhabitants of a nearby settlement.
As for historical figures who can speak and tell you all about who they've killed, I suggest a much more fluid way of getting the bragging out of the way. Instead of having them list every single historical figure they've killed all at once, it would be better if they did one at a time in a way someone would actually say such a thing.
For instance, at the beginning of a fight they could say something like "Say hello to Deadguy Firstexample when I send you to the underworld!", or " I didn't beat Wimpy Weaksauce to death with his own foot to lose to the likes of you!" The latter could tie in with how injuries sustained during duels are tracked, with the braggart stating how he injured a previous opponent in some way.
As the fight goes on, the way bragging is conveyed should change to reflect the pace of the battle.
"You remind me of Mook Monkeybreath. I hated that guy."
"Come on now, Diesinonehit Letdown put up a better fight than you!"
"I haven't had a fight this good since Opponent Worthyfights!"
The way the opponent brags about past victories doesn't necessarily have to reflect how much of a fight you're putting up, or how much of a fight the previous opponent put up. The point is the braggart should brag in small increments, and more importantly putting at least a little variety into how they get the message out.
If they have to tell you about every single one of their kills, it should be at an appropriate time, namely when it appears as if the fight is about to end. If you're getting the upper hand and it looks like they're about to die, they might want to take the time to tell you their life's story. If you want to do away with the current method of kill bragging entirely, you could have them just give a quick summary such as, "I am Enpeecy Killquest! I have killed many foes, and you will not be the end of me!"
I just think it's a royal pain to have to wade through conversation window after conversation window just because a certain successful historical figure can't shut up about who they've beaten. Something should be done and this is all I've got to contribute to see that end met.
I'm just sayin'.