Cooldown Reduction (CDR)
A stat that shortens the time before a skill or battle spell can be used again.
Cooldown reduction shortens the wait between casts of a hero's skills and their battle spell, commonly capped around 40% naturally, with a few passives pushing slightly past that. Mage items build toward CDR because a mage's damage output is bottlenecked by how often their skills come off cooldown. Stacking CDR effectively increases a skill-reliant hero's damage-per-minute without needing more raw power per cast.