How to reach Plane of Shadow
Unless you have completed the Portal Attunement quest for Plane of Shadow you'll have to take the long route to this zone. Wizards and Druids can skip this part and port directly to Dawnshroud Peaks (or if you have a friend that can port you). Everyone else will have to make their way to Plane of Knowledge and then to The Nexus.
Shown in my map above you'll want to travel north through The Nexus to reach Netherbian Lair. Once here you'll want to travel directly south through the zone until you reach the Dawnshroud Peaks zone line - shown in the map of the area I have below.
Once you're in Dawnshroud Peaks run southeast to the Maiden's Eye zone line. The route is marked out on my map of Dawnshroud Peaks below if you're having trouble with this part.
After arriving in Maiden's Eye you're going to want to travel directly east to Umbral Plains. This route is shown on my map below; for players in our level range it won't really be a risky run at all despite all of the enemies that are in your way.
When you arrive in Umbral Plains there's only one place else for you to go and that's to Vex Thal in the bottom right corner of the map. Normally this zone would require a very lengthy keying process but by the time your server reaches Rain of Fear the key to enter Vex Thal will no longer be required.
To zone into Vex Thal from Umbral Plains just click on the large door that's at the location it says Vex Thal at on my map below.
Once you're inside Vex Thal you can find the zone line to Plane of Shadow basically just around the corner. As with all of the other RoF zones you'll be looking for a large purple crystal to click on which zones you into PoShadow.