Sophia was added in patch 3.4 of the Heavensward expansion.
Sophia becomes available at level 60 as part of the “Balance unto All” quest, which is given by Unukalhai – Mor Dhona – The Rising Stones (X:6, Y:5).
The trial has a minimum ilevel of 220 to enter and rewards you with:
Allagan Tomestone of Poetics: 15