The Sylas build for Mid is Everfrost and Conqueror. This LoL Sylas guide for Mid at Platinum+ on 13.19 includes runes, items, skill order, and counters.
52.1%
(+0.4%)
48.6%
(+0.3%)
8.4%
(+0.6%)
12.5%
(+1.9%)
793
(+8)