Frenzied Beasts Beastmasters, Donorian Clawed Fiends, Khymerae and Razorwing Flocks in a Dark Olympiad all have combat drugs in addition to their other wargear.
The Grand Finale An army that includes a Dark Olympiad rolls an extra dice on the chart when determining which combat drugs are available, and applies two of the results generated instead of the usual one. Note that an army that includes a both a Dark Olympiad and Duke Sliscus could roll three dice and choose two results.
Orgy of Scarlet Once the game has begun, whenever a unit from the Dark Olympiad gains a pain token for destroying an enemy unit, choose a Dark Eldar unit within 24" and within line of sight; that unit also gains a pain token.