The damage needs a source specified - it should read, "At the beginning of each player's end step, Shockworks deal 1 damage to each creature he or she controls that did not attack that turn."

Would this make more sense at the beginning of the next upkeep? That would make the card more useful to the red wizards, letting him pile on extra damage with sorceries, and giving all blocking creatures -0/-1 on his turn.

jmgariepy- you're right, but at the moment I'm having trouble templating that in.

Is it a problem that this prevents any new Archivists, Elvish Pipers etc living longer than half a turn?

Green kills enchantments all the time, and blue can counter or bounce it, so I don't think so.

I think it's a problem. Other cards that punish not-attacking usually only affect creatures that could have but didn't. On a static ability, it's a little harder to template. This is probably too loose, but it gets the point across: "At the beginning of each end step, ~ deals 1 damage to each creature that could have attacked this turn but didn't." That template has the "feature" of also not dealing damage to creatures if the opponent has a Propaganda-style effect.

I kind of like it killing utility creatures now.

Shrug. If you don't like it when your 4 cost 1/1 creature is incidentally killed by a spell, then don't play them. They are, after all, 1/1 creatures for a reason.

Oh, absolutely. It's just that previously you've needed to pay 4 mana for Aether Flash, or Night of Souls' Betrayal, or Humility, or Pandemonium, to doom such creatures in a way that's not itself a vulnerable 1/1. This is 2 mana.

I changed the CMC to three since I felt it was closest to Night of Souls' Betrayal from that list, but still not as strong.