This is a 8 card plus Gorex combo. You want to have all combo pieces on the battlefield except pit keeper, which is in your hand or graveyard, and at least 3 creature cards in your grave yard other than pit keeper. You need 1 mana and at least 5 life to start the combo.
To start, cast Gorex by exiling 3 creatures (including pit keeper when applicable) and paying 4 life using either defiler of flesh or post son of rich ability.
Now sacrifice Gorex using ashnod’s altar for 2 colourless mana and returning the first card to your hand from exile.
Because Mikaeus, the unhallowed gives Gorex undying it will return to the battlefield with a +1/+1 counter.
Pay 1 colourless and 2 life to remove that counter using hex parasite and then sacrifice Gorex again to get the second card from exile.
Gorex is returned again with a +1/+1, with cultist of the absolute in play its toughness should be 9 now. Pay 1 colourless to sacrifice it using disciple of griselbrand to gain 9 life and return the last card from exile to your hand.
Now discard any number of creature cards except pit keeper until there is at least 4 creatures in your graveyard using putrid imp.
Finally cast pit keeper for 1 colourless and 2 life, returning Gorex to your hand. Then sacrifice pit keeper to ashnod’s altar for 2 colourless.
This can then be repeated any number of times you would like giving you 1 life and 1 colourless mana each time. Furthermore, with something like a blood artist this will drain all of your opponents.
