This a different take on Obliterator Rock that uses Smallpox for a couple different interactions.
To explain...Deck interactions - Smallpox can discard bitterblossom or Bow of Nylea, either of these give two counters to Tarmogoyf when they hit the gy. We can sac
Geralf's Messenger
or Kitchen Finks to smallpox for utility interaction (damage or lifegain, depeding on the draw/situation). Also, we can sac Bitterblossom tokens which is generally going to be advantage us since the tokens are essentially "cheaper" than any creature spell at a cost of 1 life and infinite until our life total hits 0.
We want to slow down our opponent. Our optimal T2 play is Smallpox. Next best is Bitterblossom. Obviously these aren't our best 2 CMC cards, but we want to control threats and then crash the board with our threats. Both of these cards slow down creature strategies, while smallpox also helps against several other decks in some unique ways (see below). T3 T4 and beyond we want to be playing our beaters, looking at you Tarmogoyf and Phyrexian Obliterator.
Smallpox vs...
Burn - remove a card from hand and often will knock off a guide, swiftspear, of vexing devil as well. Also, burn runs less than 20 lands, so you may be able to mana screw them if they keep a 1-2 land hand.
Tron - tron is all about lands making big manas, smallpox makes you discard and sac lands, so its a pretty effective card here. The discard aspect helps prevent fetching lands as well.
Infect - At its core it is a fast creature based combo deck. Again, we are disrupting tempo by forcing discard and land sac (maybe even an inkmoth) and perhaps knocking off a threatening creature.
Scapeshift - Scapeshift is all about having lands and taking time to get there. Haven't tested this but it should be one of the easier match ups.
Delver variants - Not sure what to make of this, I haven't played against delver much in my meta. Love to hear from the community here.
Beast Within
Beast Within can knock off another land if the opponent is behind lands due to Smallpox. Yes, they get a 3/3 creature but you have Tarmogoyf and Phyrexian Obliterator. Beast Within can also hit your Bitterblossom or Dark Confidant on their end step if your life total is getting dangerously low and you get a 3/3 to swing with that they didn't see coming. Also remember you can hit
Geralf's Messenger
or Kitchen Finks on their end step to get the token and provide the life loss/life gain triggers these utility creatures provide.
Would love to hear some thoughts as I keep adapting the list!