Wait a second here... What's going on here? Even if that added just a single this card would be highly questionable. Currently it's a walking Sol Ring. The thing to remember is that Worn Powerstone is quite playable so Sol Ring is just right-out insane.

A good place to look for comparisons would be the Myrs: all the ones that tap for a single colored mana cost . The one that taps for costs (and is a 2/2).

Mmm, being on legs makes it more vulnerable; but probably not enough more vulnerable to be this cheap. Which is a shame.

Still, I could see this at ; the set really wants colourless in quantity.

Well... Maybe if you make it a legendary too (though I already hear EDH players groaning).... and perhaps some kind of negative dies trigger.

The name has some interesting flavor possibilities. What if it changed controller after dying (ala Treacherous Pit-Dweller)? Wait, that might actually make it more powerful if you back it up with a pinger... but in an interesting way...