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
A Few Parting Decks These are the last recent lists I have from our Gladiator league leftover from before Zendikar Ris-ing
Gloomdrifter gives you another mass debuff effect, and one that only affects nonblack creatures
Thematically, this is a great card, as it is an artificer and it makes artifact tokens
Jack OP08-084 (One Piece Japanese Two Legends | One Piece Cards) prices are based on the historic sales
For a long stretch of time, the Design team was doing a lot of work to try to create a Constructed-viable red planeswalker