Treasure Map Treasure Map is easily one of my favorite cards of all time
Guild Artisan is also a good option for B/R because of its treasure generation
You could choose one and spare most of your creatures while surely removing most, if not all, of the creatures on opposing battlefields
Like Auras, Equipment can be attached to creatures to power them up
For decks with three or more colors, where you might only be able to afford a small number of MDFCs since you'll need most of your lands to either be basics (for ramping / tutoring purposes) or tap for multiple colors of mana, the best MDFCs are Bala Ged Recovery (seriously, if you have green mana in your deck, play this card), Valakut Awakening, Hagra Mauling, and Ondu Inversion, along with the mythic cycle, which is almost always good if you can afford another land that only taps for a single color of mana