Hapatra, Vizier of Phyrexia (EDH / Commander) [Revision 26]

Kill 'em all

Hapatra, Vizier of Poisons + Yawgmoth, Thran Physician - Creature lock, along with card draw limited only by your life total. You need one creature to start the loop, where you sacrifice said creature to Yawgmoths ability, put -1/-1 counter on the opponents creature, triggering Hapatra to get a new token to sacrifice and start the loop again.

Yawgmoth, I've come to bargain

Hapatra, Vizier of Poisons + Yawgmoth, Thran Physician + Young Wolf - What if opponents run out of creatures ? Well, you need to put -1/-1 counters on something that won't die so easily, which brings us to Wolf. While looping with Hapatra and Yawgmoth simply sacrifice the snake and put the -1/-1 counter on Wolf, triggering its undying ability and returning it to the battliefield with +1/+1 counter. Another negative counter negates the positive one from undying so it can be triggered again.
Hapatra, Vizier of Poisons + Yawgmoth, Thran Physician + Nest of Scarabs - Similarly with 2 token producers out, you can sacrifice one token to put -1/-1 counter to another, getting 2 fresh tokens for your effort.

Thats cool and all, but I'ma be dead...

Hapatra, Vizier of Poisons + Yawgmoth, Thran Physician + Blood Artist | Zulaport Cutthroat | Obelisk Spider - With Hapatra and Yawgmoth you are not only drawing cards, but also triggering death triggers and placing -1/-1 counters. However with one of the aristocratic trinity out there you are effectively draining the opponents for their life, while maintaining your own !

Spread wide ( ͡° ͜ʖ ͡°)

Hapatra, Vizier of Poisons + Devoted Druid + Ivy Lane Denizen - You can create an army of infinite deathtouch snakes if you are rather going wide instead of sucking life from your opponents. You need to put the -1/-1 counter on the Druid (This is not affected by summoning sickness, and you can do it with untapped Druid) triggering Hapatra, giving you the snake. This will trigger Ivy Lanes ability to put +1/+1 counter on a creature, in our case the Druid.

Just another mana dork

Hapatra, Vizier of Poisons + Devoted Druid + Ivy Lane Denizen - This is the same combo as mentioned above, however for this to work Druid can't have summoning sickness, so you can tap it to produce mana

You can find more budget friendly version of the deck here.

And even more budget friendly build here.