The following compares the current state of Frost Mages to Shadow Priests using the latest SimulationCraft data for end-game PvE in World of Warcraft The War Within patch 11.0.2.
Comparison
Category
Winner
Frost Mage
+12.59%
When simulating boss fight encounters, Frost Mages averaged +191,298.55 more DPS than Shadow Priests, a 12.59% increase.
Shadow Priest
+11.87%
When simulating AoE DPS, Shadow Priests averaged +383,637.83 more DPS than Frost Mages, a 11.87% increase.
Shadow Priest
+40.21%
Shadow Priests have higher burst damage potential, achieving +1.9M more DPS than Frost Mages.
Note: this is the highest temporary DPS achieved in any given moment and is not sustained DPS.
Frost Mage
+0.51%
+44 ilvl improved the DPS of Frost Mage by 67.45%.
+44 ilvl improved the DPS of Shadow Priest by 66.94%.
When comparing how both specs scale with gear, Frost Mages had a higher DPS increase, a +0.51% higher increase than Shadow Priests.
Shadow Priest
+7.36%
+ Movement and latency lowered the DPS of Shadow Priest by 7.99%.
+ Movement and latency lowered the DPS of Frost Mage by 15.35%.
When introducing occasional movement and real-world latency, Shadow Priests were less affected with a 7.99% decrease in DPS, whereas Frost Mages suffered a higher loss of 15.35% DPS.
Frost Mage
When evaluating abilities used during boss encounters, Frost Mages had fewer damaging abilities in total, indicating a potentially less complex rotation.
The comparisons above highlight some of the key differences between Frost Mage and Shadow Priest in the current meta, which can hopefully help you determine which spec to play or group up with.