Eternal Scourge is really valuable in this type of strategy. For the most part from playing against this particular commander a ton, the way to deal with her is to exile everything all at once or bounce everything and then do a Windfall type effect. Eternal Scourge can be awesome in these situations. As for what to cut, no clue. I can say that its addition to a few of my friends decks have made them much harder to deal with. Rune-Scarred Demon is also amazing as a tutor and puts out that big old body. I also really think Liliana, Death's Majesty would be worth a spot if you can find room.

Thanks for awesome suggestions Hyperalgialysis!
I'll definitely try Eternal Scourge even though I won't probably need it yet. We are all newbies in my play group and there is very little control. It could come in handy later though!
I won't add Rune-Scarred Demon yet. I already run Sidisi, Undead Vizier + handful of creature-only tutors while the rest of the group runs 0-2 tutors. I'll wait a little bit for them to catch up.
I really like Liliana, Death's Majesty. She does everything my deck wants to do! I'll be sure to get her next time I'm spending cash on MtG.