Crowd control spells are those which mass-stun/freeze or have specific debuffing, distracting or confusing the opponents to slip out of tight circumstances.
If you use these, you cannot get the achievement. Slowing, chilling or burning effects do not count. For example, Slow Time can be used without limitation.
Some that I know of:
- Blinding Flash
- Crippling Wave(*)
- Seven-Sided-Strike w/ Pandemonium (stun effect)
- Spirit Walk
- Mass Confusion
- Smoke Screen
- Shadow Power(*)
Also, having a freeze / stun property on your weapon or any other item also disqualifies you from the achievement. Even a 1% chance counts.
(*): Unsure of these. Have not tested yet.
There might also be more to add (Crusader, anyone?).