This needs more Kavu Predators
I agree the card works great, but it isn't necessarily needed maindeck. If he concentrates the maindeck on the combo, he could always side in the predators as Plan B for games 1 and 2. I would also side out the Refreshing rains for Duress. cut 1 Invigorate for Deed #4, and cut the birds for Nev Disks.
The purpose of the deeds and disks is to stall until you can sculpt you hand to combo off. More than anything else, I use the rituals to cast early disks and deeds. You don't need the birds because you combo is

. If you drop the birds first turn, you have 3 mana up which isn't necesary. If you need 3 mana, ritual so you can duress and the FC.
Lands
7 Forest
4 Llanowar Wastes
3 Swamp
4 Tainted Wood
4 Urborg, Tomb of Yawgmoth
Are trying to build the optimal build, or are you building based upon the collection you own? If you want the optimal build, you want at least 4 bayou and 4 overgrown tomb. You
HAVE to have a
FOREST in order to cast the stuff for free, so I would go with this mana base:
8 Green Fetch
4 Bayou
4 Overgrown Tomb
4 Urborg
2 Forest
So essentially, this is the list I would now consider going with:
4 Skyshroud Cutter
4 Reverent Silence
3 Invigorate
4 False Cure
4 Dark Ritual
1 Demonic Tutor
4 Infernal Tutor
1 Vampiric Tutor
1 Yawgmoth's Will
4 Neverryl's Disk
4 Pernicious Deed
4 Duress
Sideboard
4 Refreshing Rain
4 Kavu Predator
4 Leyline of the Void
3 ?
Goldfish that. The only other thing I would consider trying is to swap the infernal tutors out for either Night Whisper or Infernal Contract.
j