Depending on how you want to drain, there are combos with hulk that win on the spot with a sasc outlet.

Putrid Goblin , Melira, Sylvok Outcast , and Blood Artist or Zulaport Cutthroat is infinite sacrifice (and is much more budget than Mike/Trik).

In my playing of Meren, I cut Gonti and Massacre Girl. To me, they dont do enough for the mana. I see that you are playing Jarad, so maybe you can play his best friend Lord of Extinction . If you have a measly graveyard of +- 10 cards, he can easily be a big threat to throw around/sac for damage/milling.

You could do with the cheap reanimation sources like Animate Dead or Victimize for some easy big threats.

Aiding I don't like Melira, Sylvok Outcast as if I only have that then it is a dead draw without the rest of the combo. Mikaeus, the Unhallowed at least allows all other creatures to come back once.

I am thinking of cutting Gonti, Lord of Luxury eventually. I'm keeping Massacre Girl until I can replace her with Massacre Wurm . I like Lord of Extinction but I keep forgetting about it so I'll add it to the maybe board now so I don't forget.

I already took Victimize out the deck for Whisper, Blood Liturgist as for one more mana I got a lot more uses out of it. I don't like Animate Dead because of all the ways to get creatures out of the graveyard i would have to wait for it to die to use it again.