Cinder Drift was added in patch 5.2 of the Shadowbringers expansion.
Cinder Drift becomes available at level 80 as part of the “Ruby Doomsday” quest, which is given by Resistance Officer – The Lochs (X:36, Y:31).
The trial has a minimum ilevel of 455 to enter and rewards you with:
Allagan Tomestone of Poetics: 12