You said you like mass removal, and Austere Command comes to mind. Also if your play group wouldn't hate you for it, maybe a Sheoldred, Whispering One ?

Sorry, Freudian slip. I was thinking of praetors but meant the white one, Elesh Norn, Grand Cenobite

Here's my version -

1. Cut Harvester of Souls . Add Necropotence and/or Phyrexian Arena .
2. Cut land that comes in tapped, except Bojuka Bog .
3. Cut slow removal like Magus of the Disk .

The most competitive EDH decks can easily win around turn 4. This is taken from 1v1 EDH matches. With combos this can apply to group games too. If you actually do want your deck to stand a chance in a hyper competitive environment you need to make sure that you're drawing exactly what you need every turn - add a lot of tutors like Demonic Tutor etc.

Deadbridge Chant , Liliana Vess , Awakening Zone , Dread Return , Vigor Mortis , Savra, Queen of the Golgari , Elesh Norn, Grand Cenobite , Vorinclex, Voice of Hunger , Teysa, Envoy of Ghosts , Jarad, Golgari Lich Lord , Deathrite Shaman , Braids, Cabal Minion