Crystal Maiden or CM (in-game name) is recently my favorite DoTA hero. But first, please read her background story.
Adept in the manipulation of frost and ice, Rylai is the very image of elegeance and grace. Trained by a renegade wizard deep in the heart of Winterspring, Rylai brings to the Sentinel her prowess in the arts of magic. With a vast arsenal of spells, she wreaks havoc upon her foes - be it with powerful blasts of frost to send them fleeing in panic, or be it by rendering them immobile in ice. Her foes tremble in fear as the ground beneath implodes in mighty novas of frost in a dazzling array, obliterating all who dare oppose her.
Considered an intelligence spellcaster and disabler support hero, meaning she's in-charge in taking care of her teammates especially the Carry/MVP heroes. Anyway, Crystal Maiden's skills include Crystal Nova, allows her to blast multiple enemies with a chilling damage. Frostbite freezes a single enemy target disabling them for several seconds. Brilliance Aura, the best passive skill (which I believe) of all heroes in DoTA, talk about global fast mana regeneration so your teammates can spam their active skills. Lastly, Freezing Field, it causes random icy explosion on Crystal Maiden's surrounding area, all enemy units affected by Freezing Field are slowed down and damaged. Although she tends to be not the game's superstar, but still she's the most-sought, most valuable and hottest (the racks and curves, of course) hero in any team.