The game was designed with the thought in mind that there wouldn't be a great deal of CC, nor would it be highly necessary. Originally priests were supposed to have the CC spell, but this was moved to mages, and then the spell itself was changed.
Rogues have sap - a pre-combat mez
Mages have polymorph, which changes a creature into a sheep for a bit. They also have frost nova, which serves as a brief AE root.
Warlocks have their succubus mez and also a once-per-half-hour banish spell that lasts for 30 seconds
Druids have a very unreliable root spell
The only other CC in this game is tank-mezzing.
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Only the exceptions can be exceptional.