From Dota 2 Wiki
Main article: Runes#List
- Reduces the cooldown/replenish time of all spells and items.
- Affects cooldowns of active and passive abilities.
- Visually reduces the cooldown of Tranquil Boots, but does not affect it.
- The cooldown reduction is not updated dynamically. Only abilities cast while having the buff get their cooldowns reduced.
- Besides the mana cost reduction on items, all reductions are reflected in the ability tooltips.
- Only affects the activation cost of spells. Mana cost over time is not reduced.
- Stacks multiplicatively with the cooldown reduction of Octarine Core.
- The buff of multiple Arcane Runes does not stack, but refreshes the duration instead.