Passive: Dagath feeds from the souls of the deceased, granting her a 35% chance to activate Abundant Abyss when picking up Health Orbs or Energy Orbs to increase their effective yield by 300%. Wyrd Scythes - Wyrd Scythes surround Dagath and seek out nearby enemies. Those struck are slowed and suffer Viral Damage with a guaranteed Status Effect. The scythes also spread Doom and extend its duration. DOOM Not Eternal (15sec edition) - Condemn nearby enemies to their DOOM. A portion of the damage Dagath deals is revisited upon them by a Wyrd Scythe. They also suffer Viral damage. Grave Spirit - Supercharge Dagath's weapons with extra Critical Damage. The effects are doubled on Doomed enemies. Escape fatal blows by briefly assuming a spectral form. Rakhali's Cavalry - Phantom Kaithes charge forth, inflicting Viral Damage upon all in their path. Their attack strips the defenses of Doomed enemies.
Acquisition: Main and component blueprints are acquired from Dagath's Hollow within the Clan Dojo. Component blueprints require Vainthorns to craft, obtained from the Abyssal Zone on Ceres. Access requires Abyssal Beacons, purchased from Faction Syndicates.
Dagath had the misfortune of being a cone-shaped AoE nuke frame that released right after the strongest (also cone-shaped) AoE nuke frame in the game. In a world without Kullervo in it, Dagath would be a strong contended for the top spot in terms of nuking potential, at least until Dante's release. Sadly for her, this isn't the world we live in. As it stands, I don't see a reason to use her over Kullervo or Dante other than for her spooky theme.
Her grave spirit augment is an interesting way to play though it suffers from its own success a bit, Free crit AND doom on all enemies is so powerful that when the ability runs out there's nothing left in a 3 mile radius to kill in order to reduce the cooldown.
While it's a strong combo, in practice it's just a more clunky version of what a lot of other frames can already accomplish with subsumed Roar and their own abilities. An unmoddable 25sec of downtime that can only be reduced by killing 25 things without your strongest buff active is not very impressive.
Even without Grave Spirit running, the armour strip and viral from her horse blast essentially just demotes enemies off Steel Path, so the 25s cooldown is more like a 3s cooldown... if you're soloing. Finding enough enemies on a squad is pain though.