Murderous Rider

4 of these in my whitr black deck for sure.

Turn 1 Healer's Hawk -> Turn 2 Ajani's pridemate (hit face with hawk) -> Turn 3 staggering insight on hawk -> hit face, 2 +1 +1 counters on ajani pridemate, draw from staggering, another healer's hawk, drop it -> opponent plays 4 mana creature on turn 4 -> play gideon's company, hit face with healer's hawk -> save mana for next turn to drop murderous rider

Actually scratch that.

Thats three colors

You would need Dimir or Simic Guildgates