What's the Assassin Darius build?

maybe? ass loads of damage and ultra fast due to Deadmans + Trinity passives, Rage passive if you land even a single auto, and Youmuus/Mercurial actives for when you need to be Hecarim for a couple of seconds.

But youre still Darius so you definitely get to enjoy the padded defenses of DMP/Mercurial/Guardian Angel along with Trinity+DMPs bonus health. Your first auto gets empowered by Sheen + Duskblade's 99% slow and DMP's Momentum stacks discharging all at once and they just explode.

Why bother when you can go Trinity into Sterak's and literally out-trade anyone that can't lock you down and kite you?

Plenty of burst and sustained damage, plenty of durability.

Its the build where you get QT to stab you in the back real good

just build lethality and pretend you're a zed that never learned how shadow ninjutsu work.