@Arianrhod: Brael did a lot of work w/
Dark Confidant, which also plays well w/ stuff like
Walking Ballista. As for (potential) CA creatures I've been dabbling with:
-
Tireless Tracker: As you said, can steal games but takes a
lot of mana
-
Courser of Kruphix: Conditional CA. Even skimming off a land from the top of your library means you're one turn closer to drawing what you need. Works very well w/ manipulation like
Mirri's Guile and
Sylvan Library. Even without further manipulation it helps you time your shuffle effects, which can be the difference between life and death. Creates a neat little loop w/ the two Towers &
Dryad Arbor
-
Meren of Clan Nel Toth: Conditional CA. Sucks vs. GY hate, sucks in the early game, can be an absolute beast in the late game.
-
Vizier of the Menagerie: Conditional CA, probably worst of the bunch. Can be useful in an extremely creature heavy list. Has the same other benefits as Courser.
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Eternal Witness: In multiples. Can be awesome and backbreaking, can be mediocre.