As discussed at Aeran Intelligencer, we need a new small creature with an Enlighten trigger ("Whenever you draw a card"). Ideally it shouldn't tread too much on the toes of Aeran Intelligencer or Aeran Priest (or Nimbus Elf), but it absolutely needs to be common-suitable, and fairly black or blue-black.

That... doesn't leave much. I don't think repeatedly giving something -1/-1 is common-suitable (Weed-Pruner Poplar was pre-NWO). -1/-0 or -2/-0 is a bit too blue, not leaving much for black to be supplying in the card (because although black can provide flying on gold cards - see Sewn-Eye Drake - it would feel very odd for it to do so on a blue-black card).

Mill like this was the best I could come up with after a brief brainstorm, but I'm very happy to receive other suggestions. There isn't much in-set for it to synergise with, so something else might be better.

We seem to be settling on two broad categories of Enlighten effects - those you get for free every time you draw, and those which cost such as Psychomancer; the latter category are very nicely triggerable by any manacycling card, and we can get more powerful effects that way if we want them.

I like the name.

I agree mill is the best we have for now, but it would be nice to do something else if we can. It could be a one-off if another card had enlighten. And we currently have space for two UB cards, though one of them is currently vanilla, so two different ideas would be nice.

Later on we're likely to want to standardise costs for enlighten effects at least at common, but for now we should certainly try all possible different things and see which work best.

What if it was Enlighten — You may remove a counter from target permanent? That would be nice against mono green, mono blue, and planeswalkers. It's also a black ability that feels pretty blue as well.

Note that I do like seeing Jace's Erasure on a creature.

Ooh, I really like "remove a counter". I always liked Thrull Parasite and wished Spinal Parasite had been less nerfed. I hadn't actually realised I was designing Jace's Erasure :) Core sets are one thing, but for a card in an expansion to mill there ought to be something of a theme rather than being a complete oneoff. And I don't think we'd want to make mill a subtheme just of the blue-black Aer cards, and it certainly doesn't make sense to be a theme of all of Aer.

I like that. It fits the feel of Aer holding back the tide of mono-coloured creatures. And I think it could work outside of block without being broken (eg. work with dark depths less dramatically than vampire hexmage).

Although I'm not sure if it should be common or uncommon, it's the sort of card that will do little in some matchups, but dominate others. Is that OK for common?

Re: mill. I think there was a mill subtheme in blue, which means there probably shouldn't be on multicolour blue cards. A multicolour mill theme would be interesting, but we've not decided to go there.

I was thinking about this some more and I realised it really is quite a hard hoser for blue flood. Even with a mana cost on the trigger it still un-floods your lands more efficiently than I think we want from a common... Or perhaps even from any card in the set.

I can imagine a mono-blue player throwing up their hands in disgust and saying "You have that? Then none of my big creatures can attack you, half of my spells don't work against you, we may as well move on to game 2... and hope you don't draw it then."

Oh! Except, of course... that you'll probably have islands anyway if you're playing a blue-black card! :D Um... ignore me :)

Indeed. Mono-blue doesn't need to flood a blue player's lands. :)