See Challenge # 106b // Challenge # 106b.

My instinct says that a non-cantrip Crippling Chill, or half a Frost Breath, needs to cost more than 1 mana. But Hands of Binding does that plus cipher for 2, so maybe it is okay at just 1.

I'm not sure about that effect in white. It's done it once or twice - Kor Hookmaster - but I'd say it's primary in blue, secondary in green.

Hm, maybe. It was originally just "tap target creature", but I thought that might be too weak. Once most of the cycle was one-mana effects I wanted to keep that up if I could. Also notice this is sorcery (it needn't be, but another in the cycle was iirc).

I guess I was thinking of detain, which is exactly that. But that mightn't work outside RTR. Again, just "tap target creature" might be ok? I didn't realise that was in green at all?

Now interestingly, "tap target creature" would look pretty out-of-place in green. But "tap target creature and it doesn't untap in its controller's next untap step" has a fair amount of precedent in green, particularly the Orochi in Kamigawa such as Matsu-Tribe Sniper :) I guess it's not been seen much since then though, except for Entangling Vines which was seen as a bit of a colour-bleed.

I certainly think that just "tap target creature" on its own would be poor. Cf Niveous Wisps. So this is probably fine. I'm certainly happier with it on here than with the effect on Heel // Tow :P