Grixis combines red, black, and blue in what is commonly called a shard. These three colors allow for a weird mix of chaos and control strategies, upsetting your opponents' games while keeping your own on track as much as possible
While this isn't an automatic include in a discard focused deck, it certainly is a value-packed card if you choose to run it
All in all, we've now reached a point in time where we have quite a few clone options available at two mana
When you put the "extra level" removal spell in your deck beyond the tier one options (Lightning Bolt, Path to Exile, Fatal Push) you are looking for some major upside, either in card advantage like Kolaghan's Command, or in versatility like Assassin's Trophy
To activate a craft ability, you need to do three things: exile the permanent with craft, exile the specified materials, and pay some mana