The Orianna build for Mid is Luden's Tempest and Phase Rush. This LoL Orianna guide for Mid at Platinum+ on 13.24 includes runes, items, skill order, and counters.
Orianna Counters
51.4%
(+0.3%)
53.0%
(-0.3%)
6.3%
(-2.8%)
1.1%
(-2.2%)
751
(-19)