The obvious masteries are: attack speed, bonus on-hit damage, feast for sustain in lane, armor pen over magic pen.
What I'm curious about is this:
Does DFT work out with Rend? If the dot kills the target, does Kalista get the rend reset? (I'd like to test this, so if y'all want to group up let me know)
If not, then Fervor of battle sadly becomes Kalista's only real option there, and that makes the new mastery system feel a little less cool.
Runic Affinity seems like it would be a very nice mastery to have on her because of her objective control. (and because red)