Replace Hero's Downfall with Vindicate and add Utter End.

These are just general recommendations.

False Prophet, Magus of the Disk, Merciless Eviction for mass creature removal.

Reassembling Skeleton and Nether Traitor for good chump blockers that can take advantage of Athreos' ability and show back up from the graveyard to harass the enemy.

Dictate of Erebos and Grave Pact for added security.

Skullclamp, Butcher of Malakir, and Phyrexian Arena for some card draw.

Weathered Wayfarer for more mana.

Let me know if you like these.

LastProtagonist I do like the Magus of the Disk in reference to Merciless Eviction I was running it, but I found I was always to scared to use it as it would hit a lot of my stuff without the benefit of Athreos. I can test it out though. Skullclamp and Phyrexian Arena are both supposed to be in here xD I just have not been able to get my hands on them. Also, I found that with Grave Pact and Dictate I was not getting nearly as much worth as you would think. I am typically just field wiping so all creatures are dying so I found they did not do as good as you would think.

Throw in a couple sac engines to wipe your board/kamikaze an opponent before using Merciless Eviction and you'll still be getting a lot of bang for your buck, but I suppose it depends on what kind of opponents you're facing. I have a friend who likes spawning tons of giant indestructible creatures that have recursion, so for me, a boardwide exile is needed.

I will give it a shot and see how it goes and comment back on how I like it!!

Altar of Dementia

Okay so I have done a lot of changes to the deck recently.

For draw power I added Mind's Eye. Promise of Power. Phyrexian Arena, Staff of Nin

Some Creatures of Worth Nirkana Revenant. Fleshbag Marauder, Shriekmaw, Wurmcoil Engine

Some other things I added are Palace Siege, Cabal Coffers, Corrupt (until I csn get my hands on an Exsanguinate ) and Nevinyrral's Disk Elspeth, Sun's Champion

To do this I took out a few of the planeswalkers and other assorted cards that were not doing as much to the deck as I had hoped. I also have been considering running an Ugin, the Spirit Dragon My only worry is that with my large number of non-land permanents that I run, it will only hurt me. Further testing will be needed.