Riot Games released a limited skins store.
It’s hard to say on what occasion. Perhaps Taric will receive some skin soon, or one of the employees decided to surprise the players.
Either way, you can now buy skins from 2016.
Emerald Taric in 2019
The skin first appeared in 2016, now Riot has valued it at 520 RP.
No date has been given until when the skin will be available.