Reminds me of Vectis Dominator, but is significantly better. You could say this is strictly worse than Minister of Impediments, because "Tap target creature" is always better than "Target opponent chooses - tap target creature, or awful thing". But both options are good (unlike Vectis Dominator) so this doesn't want to be 2 mana. Perhaps the P/T could become a little bit larger.

I'd disagree with "Always" better. This does seem prebuilt for horrible tricks involving incubating -1 counters on your own stuff. Seems usable to me as it is.

I was playing around with removing the untapped creature restriction to make this "I put a -1/-1 counter on target creature unless you tap it, what? it's already tapped ? awwww.
I also played around with "tap target creature and put a -1/-1 counter on it" with an activation cost.

Thinking of going back to doing both with activation cost.

That would be powerful. Probably not insanely so though.

It'd be a sakura tribe withering tim ... ok, so it's pretty powerful. Still, with a cost of 2 or 3 and it'd probably not be unreasonable.

That'd be pretty much Vedalken Anatomist. Which had quite a hefty cost. Even Gnarled Effigy charged you per pop.