Death and Taxes is all about value creatures. They all provide good effects while also being good at white weenie's specialty, beating in faces with tiny little dudes.
4x AEther Vial
Drop things in unexpectedly and uncounterably
.
2x Anafenza, Kin-Tree Spirit
The bolster triggers are nice, but she's the creature I'm most iffy about. I don't know what other 2-dro would be good in her place, though.
2x Brimaz, King of Oreskos
A 3/4 for 3 that drops more bodies when he attacks or blocks. Seems pretty good for helping with the beatdown plan.
1x Aven Mindcensor
Shut down searching.
3x Blade Splicer
4 power across 2 bodies, 3 of which has first strike.
2x Dryad Militant
Weakens delve and snapcaster, and its a 2/1 for 1.
2x Judge's Familiar
A flying one-drop that can disrupt crucial early plays. Cursecatcher in the air seems strong.
4x Flickerwisp
Blink things to save them or get them out of the way. Good for removing counters from things like Vials, Engineered Explosives, and anything stacking +1/+1 counters. Also provides a decent clock with 3 power in the air.
3x Grand Abolisher
Lets me put down my creatures in peace on my turn.
4x Leonin Arbiter
Says "No." to searching decks.
2x Restoration Angel
Flickerwisps 5-6 on a 3/4 body.
4x Thalia, Guardian of Thraben
Helps vs the control matchup, and vs aggro to an extent.
2x Vryn Wingmare
Thalia 5-6 with flying over first strike.
4x Path to Exile
The removal available to us.
2x Cathedral of War
Since I didn't spash green for Qasali Pridemage or Noble Hierarch, this provides me with Exalted.
1x Eiganjo Castle
Prevents 2 damage to a legendary creature (Thalia)
1x Flagstones of Trokair
A land that I don't mind getting nuked.
12x Plains
4x Ghost Quarter
Land removal at any point, especially strong with Arbiter
and Mindcensor.
2x Tectonic Edge
Secondary land hate.