Put it on an opponent's creature with a toughness of 2 or less and then tap to give it +2/-2, it dies?

~SE++

The gatherer says that only the aura's controller can activate its ability though. Why would they ever activate it?

Because you control the aura. Your opponent has the creature, but the aura is yours, even if it is on their creature.

~SE++

Ah, I see. That's pretty good then. Thanks for the clarification.

Pack 1:

Eternal Dragon
Lightning Helix
Kindle
Stone Giant
Lightning Angel
Flowstone Embrace
Quicksilver Amulet

Next...

Boreal Griffin
Tahngarth's Glare
Plague Rats
Channel the Suns
Bottle Gnomes
Engulfing Flames
Murmurs from Beyond
Choking Sands

we're never getting a snow land, but I'm legit thinking about Griffin just as a 3-power flier. those are like never bad. Glare is trrbl, Bottle Gnomes is a nice roadblock since we're looking late-game-y, and Flames is technically removal. note that we know a white card is missing from this pack, I should probably go back and check for more signals that maybe that's not so open because we haven't been picking much.

I'm gonna say Gnomes

I'll take the griffin. 3 power in the air, even if it's pricey.

I love Tahngarth's Glare for the flavor, but the pick is gnomes.

Engulfing Flames

We've seen Neurok Invisimancer, Clergy En-Vec, and Iron Myr as playable 1-toughness creatures. Engulfing Flames is great against all of those, Bottle Gnomes is mediocre because none of them are ever going to get blocked. Best case, it's cheap instant-speed removal with card advantage built in, and in the worst case, you can flash it back in the same turn for the most expensive 2 damage ever.

Boreal Griffin is good but I'd maybe rather have something to do early game since our curve is really high right now.

Flames. Geistflame was amazing.

You put Embrace on an opponent's creature, and then tap the enchantment to give the creature +2/-2. This kills a 2-toughness guy. Or you can do it in combat, to make a scary monster trade with your bear. But I wouldn't recommend that.

Edit: Never mind, I missed a page of posts. This pick is Geistflame for me.

Flames.

Flames or gnomes.

Engulfing Flames

It can be a decent trick once you deal some combat damage and then exile the creature with 1 last point.

~SE++

Flames.

Pack 1:

Eternal Dragon
Lightning Helix
Kindle
Stone Giant
Lightning Angel
Flowstone Embrace
Quicksilver Amulet
Engulfing Flames

Next...

Darksteel Pendant
Lure
Duskworker
Quillspike
Arnjlot's Ascent
Roiling Terrain
Oppression

Duskworker is surprisingly decent.

Is that supposed to be Roiling Terrain?

I can get behind a ", : Scry 1." Darksteel Pendant takes my vote.

I almost want to hate the oppression because a decently fast deck with that is gonna steamroll us.

on-color, though, we have pendant, worker, and roiling terrain. (not rolling.) the terrain isn't likely to help us, it's just an expensive stone rain. worker I kind of like because it's very difficult to block profitably, just from threat-of-activation, we can pretty reliably safely swing through 4-toughness dudes, and if they block hey free card. on the other hand at best it's a 2/2 unblockable for 4, which isn't bad but isn't mindblowing. the pendant takes another approach: this deck is gonna be a lot of jank. our opponent's deck is gonna be a lot of jank. if we can get rid of ours to get to our good stuff and they can't, we'll have a serious advantage. I think this is a format where filtering is much better than usual, but I'm still gonna say worker 'cause the world's worst phantom warrior is still a phantom warrior.