Since youre taking advantage of your opponents graveyards, its a good idea to help them fill it
How many Game Changers are there
Loxi: Ironically, I think most people will play this for the Cyclonic Rift part of the second bit and just use this as great mill/discard-fodder
Aside from these artifacts, the deck uses white for cards like Disenchant and Swords to Plowshares to be able to survive until it can set up a lock, and it can also use blue for counterspells
If you're the sort of player who enjoys seeing what everyone else has on the board and playing it yourself, Volrath is worth giving a go
In general you want to save the Sidisis Faithful to set up one big turn where you clear their legendary creature and go off, but there is an exception when you have a Rally to spare, either because you have two or because you are just going to beat them down regardless