From Dota 2 Wiki
Health Regen Bonus per Stack: 1/2/3/6
Mana Regen Bonus per Stack: 2/4/6/12
Stack Duration: 6
Prevents gaining new stacks. Already existing stacks still provide bonus health and mana regeneration.
Sadist Counter: Dispellable with any dispel.
- Sadist triggers on every kill Necrophos makes, including denying allied units, but excluding illusions and Tempest Double
- All stacks work fully independently from each other. They do not refresh each other, but share a status buff. The number of current stacks is visible on the buff.
- Restores health and mana in the form of health and mana regeneration, so it regenerates 0.1/0.2/0.3/0.6 health and 0.2/0.4/0.6/1.2 mana in 0.1 second intervals per stack.
- Each stack can restore a total of 6/12/18/36 health and 12/24/36/72 mana.
- Hero kills add 10 stacks at once, regenerating a total of 60/120/180/360 health and 120/240/360/720 mana.
- Although the Sadist counter buff is dispellable, doing so has no effect, as it gets immediately re-applied.
Mana Restored per Non-Hero Kill: 12/24/36/60
Mana Restored per Hero Kill: 12/24/36/600
Attack Damage Reduction: 9%/18%/27%/36%
Diffusion Aura: Undispellable.