Seeing that the creatures themselves are kinda small, you're relying on the "Rally" triggers, removal and the speed of the deck to win in standard games. "March of the Tomb" is in here so that once enough things die, you can reanimate as many creatures that trigger all the Rally they can.

There's a lot of exile in this set. For that reason, it's good to run multiple copies of the creatures that you think will win the game. I don't see much room for small Allies that don't have a Rally ability because people will choose to remove Rally Allies rather than the generic Allies. "Felidar Cubs" help remove enchantments that hinder you and it can serve as a decent attacker while Rally abilities are active.

"Complete Disregard" is good for exiling the opposing Allies you really don't want coming back and small annoyances.

My thoughts on "Planar Outburst" and "Rising Miasma" was to cripple the decks that have a surplus of Eldrazi Scion spawners and other Allies that rely on rally.