My friend's been asking for a 1v1, where he'll be playing Yi. It'll be mid lane, not sure about jungle farming and etc.
Anyway, from the limited champ pool I have, I was thinking I would pick either Riven or Xin against him.
Both are decent early, much better than yi, and both are fairly good late.
I'd build quite a bit of CDR on Riven, probably ionian boots + brut and maybe even fro heart for the hell of it in addition to BT's, because the GA isn't so handy in a 1v1
For xin, i'd definitely grab a frozen heart, just because i can, in addition to a randuins, perhaps an Atma's in there.
Any additional comments?