>>537772249
I think in terms of raw efficacy it's not super crazy good, but it is very fun because Duchess' ult only has specific niche uses otherwise like the fact that you have unlimited stamina until a fight starts so if you have a long range spell you can spam it for 10 seconds before stamina starts being used.

With damage on kills during ult + kills give you additional ult charge, you can frequently use Duchess' ult to do really goofy shit. More interestingly, remember that kills are GLOBAL. That means that if you break off from your group, and they kill things while you're in your ult, you get the damage buff regardless. Because of that, Duchess can split off from the group, pop ult, kill a few people and also get the kills from your allies in another location and suddenly be doing like 250% damage and instantly evaporate a PoI. You can also do shit like kill a few crabs on the way to the castle basement for 60% additional damage, etc.

All in all in terms of fun, it's a rock solid relic effect, and it only takes a single kill to match 3 evergaols. I've used in in ED libra to get 45% damage from the condemned, too, which is always fun.