Planeswalkers are always mythic rare. Mark Rosewater says an uncommon planeswalker will never happen. But it'd be interesting to imagine what it'd be like if it did.

Feel free to either state your imagined explanation for the flavour or structure of the set that allows them to break the current restriction to mythic rare; but equally, don't feel that you have to.

Feeling suitable for uncommon (or common) will obviously be the most important criterion here. What that looks like on a planeswalker is up to you.

Eeeenteresting. I'd say that the inherent flexibility of a planeswalker is going to make it very hard to justify one at common - but then, there's the charms.

Oh my.

Made Trainer of Ascendants, Ascended Pyromage, Enlightened Mulchtiller, Planeswalking Conscriptor, and Transcendant Sangromancer.

Made Planestrider Evangel. More later.

Made Chandra's Simulacrum, Gideon's Simulacrum, and, to spice things up, added Mairsil, the Devious.

Added Emeralda, I wondered to myself - why should planeswalkers get + abilities at all?

I did something like this with loyalty lands in Gentlemen Magicians: http://multiverse.heroku.com/cardsets/5

But those were still rather flawed. Thinking about what happened, what I think a common or uncommon planeswalker needs is:

• A flavour justification for being non-mythic. For the loyalty lands, I just used the loyalty mechanic but not the planeswalker flavour, so the cards could feel workmanlike and not have to feel super-special. (Though I used planeswalker on the type line in multiverse to get the planeswalker frame.)
• Really simple abilities. A card that can cast three different common spells multiple times is probably still rare or mythic rare. The loyalty lands often had one mana ability and one other ability, and felt to be pushing the upper end of complexity for common (and most were too complicated, but I think that could be fixed).
• Don't automatically try and have an ultimate, or have multiple battlefield affecting effects: either is probably going to warp the game a lot more than is appropriate for uncommon.
• Conversely, if there isn't a strong ultimate, don't have a strong +1 and no other strong abilities, as if the planeswalker is not automatically worth attacking, it'll become tedious to keep track of a giant pile of counters. (Which is ok sometimes, but not if there's a whole bunch of uncommon planeswalkers which accumulate counters where the exact number doesn't matter.)
• In fact, a planeswalker that sticks around a couple of turns and then is usually used up or killed is probably about right.

­Young Chandra
­Young Garruck
­Splinter of Jace

(And with apologies for accidently stealing the "young" naming sequence from the one-cost rare planeswalkers like Young Ajani)

­Jerkwalker

Thought about what made Chandra's Simulacrum work and didn't work for me. Came back to the drawing board and made Jace's Simulacrum. I think this does a better job feeling like a real planeswalker, but still keeps it common.

­Griff, the Holy

­Koth's Hammer