Haarken Greatblade is a Void affinity epic from the Barbarian faction. Haarken was added in December 2020 at the same time as the festive fusion event for the High Elves champion Pyxniel.
Haarken needs 100% crit rate to ensure additional hits form her A1 ability and will need accuracy to place the weaken debuff on her A2 and spread debuffs with her A3. Haarken has a very high base attack however low defensive numbers and therefore I wouldn’t recommend using her in the Arena unless you can ensure you hide her behind a Veil.
There are some opportunities to set up an AOE HP burn using a single target HP burn champion and then spreading with Haarken’s A3, this is particularly strong against Spider 20 if you do not have the champions to do this.
Aside from this niche situation Haarken seems to be a very average champion.