A wide variety of decks could want this as a role-playing mana rock, even at 3 mana
Tarkir: Dragonstorm Say you picked up six Tarkir: Dragonstorm play boosters for a Sealed event, you are in for some big time spells
With less of a focus on low-cost characters than Amber/Amethyst and fewer heavy hitters than Sapphire/Steel, Emerald/Ruby places a big emphasis on solid mid-range options
Robert has the ability to push his men through the thick of battle, so I gave him the ability to buff blocked creatures so they can overcome whatever is in their way
Obviously these may be a miss for your format for other reasons (power, archetype mismatch, rarity, don't run planeswalkers etc) but here's a few that I found interesting, divided by broad category rather than color: Actual Modal Dual Faced Cards: While I'm still not done reading Cosima, God of the Voyage (I'm on chapter 2, the language is a bit dense) these cards are ones I do like both sides of
FAQs How does CGC grading compare to PSA