DRK OT Rotation

I use:
(Grit off, Darkside up)
Dark Passenger - (Low Blow & Blood Weapon) Scourge - (Plunge) Hard Slash - (DA) Syphon Strike - (Salted Earth) DA Souleater - (DA) Hard Slash - (C&S) Syphon Strike - (DA) DA Soul Eater

Then go into a maintain rotation of alternating Delirium and DA Soul Eaters, using oGCDs as they are available and use more DA Soul Eaters while under Blood Weapon.

You could push Plunge back so it gets buffed by Trick attack or slashing debuffs, but I like lining it up with Scourge. They will always be available again at the same time, so I use the Plunge action on my hotbar as a cheat sheet to know when its time to reapply Scourge. You could also apply DA to the Dark Passenger at the start if you want more dps.

This: https://i.imgur.com/jXPNNcT.jpg

To open it up a bit: You want to start off with magical oGCDs that aren't buffed by slashing debuff, cause that won't be up right away, you also want to delay Scourge for one combo if there's a Trick Attack coming, after that you want to lay down all your physical oGCDs that are buffed by the slashing that'll be up by then. The precise order isn't all that important, just think magical first, physical second.