Concepting Planeswalkers

Planeswalkers were key to the marketing of Magic 2010, and Magic 2011 expanded on this by giving the planeswalkers "signature spells" at common and uncommon. So far, the core sets have been used to show off the original 5 planeswalkers introduced, one representing each color. So what direction could this be taken in the future?

I've always liked the idea of introducing gold cards to the core set in a very limited fashion, and planeswalkers seem like the ideal way of doing this. My current plan is to create a single mythic planeswalker for each allied color combination, and give each signature gold spell at uncommon. 10 gold cards seems like a reasonable number to put in a core set, and the use of planeswalkers gives them a thematic connection.

It will take me quite a bit of brainstorming before I can even come up with 5 planeswalkers I like enough to playtest, but I wanted to share the concepts I'm working on for the various color combinations. Names are strictly working titles at this point.

White/Blue - "Gareth Seaborn"
Blue's planeswalkers have been designed around the color's philosophical aspects ("control and manipulate") so I thought it would be interesting to focus more on blue's elemental associations with water and air. A merfolk planeswaker seems like a cool concept, and blue/white seems like a good pair for the related appropriate mechanics like tapping, flying, and rule-changing.

Blue/Black - "Liliana Undercover"
I want to do at least one new version of a current planeswalker, and Liliana struck me as the most interesting choice. Rather than going for redemption or a spiral into madness, I settled on the concept of Liliana on the run, forced to rely on subtlety rather than raw power. Some sort of defensive bounce/discard will likely be used.

Black/Red - "Marek the Hunter"
We've seen the "evil and crazy" take on black/red quite a few times, so I want to try something different but still in tune with the color combination. Some sort of antihero vigilante could be fitting to the combination, so I'll see what I can think of along those lines.

Red/Green - "Damar of the Hoard"
This is the only bottom-up design on the list. I designed the combination of abilities a while back, but they're a good fit for red/green and the core set. I'll wait to show him off until I've got the others finished, though.

Green/White - "Bob the Gardener"
In a game that is all about the battles between planeswalkers, what would a peaceful planeswalker look like? It would be interesting to design relevant abilities with a "not intended for combat" feel to them.