Crystal Maiden

Basic Strategy

 * Crystal Nova is a good AoE nuke that also slows your enemies. You can hit enemies from 1100 units away with it (700 casting range+400 AoE radius).
 * Frostbite is a great disable which prevents target from moving or attacking. It also interrupts chanelling spells and teleports. Unfortunately it does not prevent enemy heroes from casting spells.
 * Arcane Aura should be prioritized as it benefits the whole team greatly especially one with a strong caster/ganker line-up.
 * Freezing Field is an incredibly strong spell. But it's rather random and usually gets interrupted by your enemies very fast. Freezing Field consumes a lot of mana so use it sparingly.
 * Items like Black King Bar and Lothar's Edge are viable options to prevent your opponents from cancelling your ultimate, but CM usually won't have that much gold to spend.
 * CM can either babysit her team's carry on dual/triple lanes or roam between the lanes to gank enemies.
 * Always ward woods. Wards should be bought over and over again to provide map control through the whole game.
 * If you have a few coins to spare - always buy items that boost your survivability, or get yourself an escape mechanism like Blink Dagger or Force Staff.

Trivia

 * Crystal Maiden's mana regen aura used to be called Brilliance Aura
 * In early versions of Dota Allstars, Crystal Maiden and Lich used to share the same Frost Nova skill, but in later updates, Crystal's nova was changed to Crystal Nova and turned into a Free Cast AOE skill, while Lich's remained as a Target AOE skill