Since you're already running at least black and red, you probably have efficient single-target removal to handle that last creature if it does happen to be worth taking out
Omen cards, however, shuffle themselves after resolved , so you cant get the dragon card naturally
Urzas Incubator If you land an Ugin's Labyrinth correctly, you could drop an Oblivion Sower on turn 3 with Urza's Incubator on turn 2
Although this will not be a sideboard guide but more a how to play each matchup, I do have a short sideboard guide against most decks in Modern that you can find here
Meanwhile, even most of our interactionlike Thought Erasure to pick apart our opponent's hand, Sinister Sabotage as a counter, and Pile On as removalhave the upside of surveilling
Patchwork Banner is a sterling example of why three mana rocks are still good