The best removal spells in Standard backed up by card advantage is still a recipe for success. Mardu Control decks were excellent before the rotation, albeit with great mana that allowed the deck to play either blue or green. Without fetchlands, you can’t go into a fourth color and thus lose some power, but there’s still a lot there.
Nahiri, the Harbinger is the biggest addition. Not only is this a 4-mana planeswalker with high loyalty, but it does exactly what the deck is looking to do. A deck with lots of lands and removal spells is often going to have excess cards to upgrade, and increasing by 2 loyalty each time makes Nahri tough to kill. You also get a tool to deal with a number of problematic permanents. Pyromancer’s Goggles and Always Watching aren’t the easiest things to kill, but having a planeswalker that does all of that while sticking around for more is a great tool.
For the same reasons, the other big addition from Shadows over Innistrad is Anguished Unmaking. Having an efficient removal spell that can take care of everything is extremely important, assuming you can take care of your life total. Instant speed with universality is a great combination.
Finally, Declaration in Stone is a great removal spell that can kill anything and take care of all of the potential token creatures. This is one of the decks that can’t fully utilize the power of Declaration because the games will go long and they will get card advantage out of it, but the mana advantage matters and it’s an excellent removal spell for hard-to-kill creatures that can still be brought back by Goblin Dark-Dwellers.
The Dark-Dwellers and Kalitas, Traitor of Ghet creature base is perfectly situated for this format. These creatures will gain you tons of value and actually play well against decks with Reflector Mage. Kalitas doesn’t look that great against Reflector Mage, but you can almost always cast a removal spell in the same turn. It’s also extra powerful against decks like the BG Sacrifice deck to come out of PT Shadows over Innistrad, so playing a great Kalitas deck is definitely a good idea right now.
With lots of options for removal, card drawing, and discard spells, Mardu has the chance to be another serious player in Standard!