Cards similar to Sorin Markov

[Gorzo]

Havoc festival for cutting life.
Debt to the debtless is the drain style you're looking for.
Mindslaver and academy ruins lets you take turns infinitely from them

{Exsanguinate} also drains pretty sweet!

{Debt to the Deathless} and {Death Grasp} are pretty solid, too. There's also {Corrupt} and {Tendrils of Agony} and {Tendrils of Corruption}