One way to mitigate the lack of specialness I talked about on Gefjun Disturber is to have two or more cards for these concepts from the series: a simple common for the basic form (the form used in series 1) and an elaborate rare for the complicated version (the form used in series 2).

In this case, making it an artifact is a little odd, but I wanted a "once per turn" restriction on the ability to stop you spamming it in response to itself, so a tap ability is the simplest way to do that; and the set looks like it'll already have coloured artifacts for Knightmares so I can still make it blue. (Though I guess this could be colourless if I wanted.)

Having a common and a rare version seems like a really great idea, especially if (as you've done here) you can use a slightly different name to explain why they're on different cards. Then people can see the little one, and immediately be prepared for the big one when they see it.

It seems obvious to make this an artifact if you can, because the original is a device (?) Especially if it doesn't absolutely need to be blue. But blue is good too.

It would be even nicer if the abilities between the two could be synced up, so this is something like "take the effect from the small one and apply it to more/bigger creatures". But that's not necessary if it doesn't produce good mechanics.

"would be even nicer if the two could be synced up" - That's what I've currently done: both this and Gefjun Disturber are "doesn't untap and abilities can't be activated". Admittedly we were talking about changing Gefjun Disturber to have a power reduction, if I made a way to give it flash, so I should bear that in mind if I do make that change.

Oops, I guess they do! The difference between aura and xx,T on a coloured artifact made them feel different to me, even though the effect is exactly the same.

The obvious sync up is to have the aura also put a neutralisation counter on; even if it doesn't do anything extra. (Though.. hmm, it would make the sequence "enchant A, disenchant, enchant B - now A disables again" which mifght be interesting enough for the complexity?)