There are so many cheap rogues and assassins in black, and a lot of them tap to destroy other creatures or have deathtouch even before Mari, the Killing Quill hits the table
Source: Magic: The Gathering Main Genre Fantasy Release Date August 5, 1993 Created by Richard Garfield Character(s) Jace Beleren, Chandra Nalaar, Liliana Vess, Garruk Wildspeaker, Nissa Revane, Ajani Goldmane, Nicol Bolas, Teferi, Gideon Jura, Sorin Markov, Ral Zarek Video Game(s) Magic: The Gathering, Magic the Gathering Commander, Magic: The Gathering - Battlegrounds, Magic the Gathering: Duels of the Planeswalkers 2012, Magic: The Gathering - Duels of the Planeswalkers, Magic: The Gathering Duels of the Planeswalkers 2012, Magic: The Gathering Duels of the Planeswalkers 2013, Magic: The Gathering Duels of the Planeswalkers 2014, Magic: The Gathering Arena
an image of a Pokmon listed in the official rules
Fire Lord Azula Fire Lord Azula is a solid Grixis (UBR) spellslinger and aggro commander
60: The one obtained if you went to the movies Mew Lv
In other words, there might be other ways to beat your opponent's Summit Prowler, but you're going to desperately need your Reach of Shadows for when he or she plays Atarka, World Render