Sona, wasn`t allowed in the URF mode of season 7, do you remember it? The last season when all the runes and those big changes weren`t.
But now in this new season, with all the runes and changes coming, URF mode is ready to come back again ! With some changes, because its Christmas time, RITO allow just champions with Christmas references skins, but yeah, Sona still not allow even if she have a Chrtismas skin, my questions is, WHY ? Rito allowed Jax, which is a frog who kills everyone soo easy, they allowed Katarina, which everybody know how bad is that, but they didn`t allowed SONA, WHY NOT ? NOBODY KNOW.