As far as I can tell Explorers are un(der)-used and mono-colored decks are better than duo-colored decks. I don’t have the statistics to prove it, but if this is true the Explorers should probably be fixed to be more playable.
At the very least they should synergize with the other cards of their color(s). Currently they never synergize with Ancient Beastmaster, Hateseed, or Firebringer even when their stats are adequate from their gift. Allowing these interactions should at least make some of them playable in their appropriate decks.
The more powerful buff would be to set them all up more like Gabrian Archon, with each buff dependant on having enough lands of that type (currently 2, but 3 seems better) This would actually give duo-colored decks some viable early game creatures. It would be a cool way to make the explorers usable along with adding some interesting layers of depth to the order you build lands when playing a multi-colored deck.
The Explorers do probably need a bit of help. And I like the idea of having the buffs be dependent on the class’ styles, rather than simply Attack/Life buffs all the time.
What could be really neat is to have a new set of cards similar to the Explorers with effects like you mentioned (and preferably offer something very different from the Purple cards), but have the effects be based on your minimum number of special lands between two types. For example:
Glade Revenant (5f, 2/5) Combat: You gain X life and X mana, where X is the lesser of your Lakes and Forests.
Strand Revenant (5f, 2/2) Gift: Draw cards until their total cost is at least two times X, where X is the lesser of your Deserts and Lakes.
Highland Revenant (5f, 4/2) Gift: Give an adjacent creature +X/+0 and this creature +0/+X, where X is the lesser of your Mountains and Forests.
Bluff Revenant (5f, 2/4) Whenever your opponent plays a spell, they take X damage, where X is the lesser of your Mountains and Deserts.
I will say, however, that my instinct is most of the duo-color combinations are not underpowered (and the worst one, Blue-Yellow, just became really good again with the new synergies for Aurora’s Disciple). If there’s a reason to include more cards that work in Duo-color decks, it’s probably Variety rather than Balance.
I can agree that the cards are a little underpowered. I used them a lot in my Dual decks in recent history, though the value rarely proved itself worth while in the face of cards in it’s cost tier. Yes you get a large body that scales by mid-game, though the scaling is marginal at best and has prompted an early removal during some of my deck-crafting.
I’d like to see something similar to the larger versions of them (Soul Eater, Warstorm Champion, etc) though exactly what that would be is unclear to me at this time.
