There is a tactic in Assassin's Creed Valhalla right now with a dual flail combination that allows you to kill your opponents quickly.
The main thing we're going to be using for this build is the Galloglach armor set. This armor set gives you a buff every time you hit a melee finisher.
So what we are going to do is we're going to pair that with a weapon that benefits from that as well and that is going to be the amazing flail the Spinning Depth. If you hit a heavy finisher, it has a 40 chance to drop a Fire Bomb. Now, in my experience because I've been using this weapon a lot it's a lot more than 40. To me it feels like it happens almost every time you hit a heavy finisher. So that's really good for both dealing with groups or hitting single target enemies and setting them on fire and then we're going to equip a second flail as well. I chose the Iron Star because that also gives you more damage after hitting a heavy finisher. Then basically what we're doing is stacking damage upon damage upon damage because every time we hit a finisher we get stronger because the buff from the Galloglach armor triggers the Spinning Death has a chance to drop a firebomb and the Iron Star Perk will give us more attack damage after heavy finish as well.
Now, how are you improving this build and what type of runes are you using? Well, mainly speed runes that you’ll find in the minor weapon slots are going to be really useful because flails are a bit slower and that's going to help with that. There's also in the major room slot in the Death Speaker bow. We have another rune that will increase speed and the Death Speaker bow is also really useful for the build because we don't really have a way of healing but with the Death Speaker bow we get a window of slow motion when we hit a couple of weak points and we can basically heal from zero back up to full in a couple of seconds without the risk of getting hit. So that's going to be really useful. You could also for example use the Viper bow which you can also buy in the store just like the Death Speaker bow and then with the Curative Perfection rune. So then every crit you also get some health back and you will be attacking very rapidly. So if you got that option then I think that might also be very nice for this build.