Cosmic Insight is one of the most popular runes to take when taking the Inspiration Tree. Cosmic Insight grants the user 18 Summoner Spell haste and 10 Item Haste. But what is Ability Haste? Simply put, Ability Haste affects the Cooldown of your abilities.
So Cosmic Insight’s main purpose is to lower your Summoner Spell and Item cooldowns.
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When Should You Use Cosmic Insight
You should use Cosmic Insight on Champions that take the Inspiration Tree already. If the Champion relies on items a lot, it may also be a good idea to take this mastery because it will lower the Cooldown of those items.
It is great on Supports, especially when they build Locket of the Iron Solari, and even on Mid laners and Junglers that build Protobelt.
Even if your Champion doesn’t rely on items, it still lowers the Cooldown of Summoner Spells. For Champions like Twisted Fate, who want to Teleport around the map, this mastery can be crucial.
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Cosmic Insight Ability Haste Chart
Combing Cosmic Insight with Boots of Ionia will lower your Summoner Spell Cooldowns even further. Even better if you’re a fan of ARAM, you will receive even more Summoner Spell Haste from the Howling Abyss Aura.
I’ve included a chart above that will explain just how much lower your cooldowns will be when receiving all of these buffs.
In summary, you’re going to want to take Cosmic Insight on Champions that want really low cooldowns on their Summoner Spells and items. Champions that take Teleport, for example, will benefit greatly because they’ll be able to impact other lanes a lot more.
It will also help Champions that rely on items like Protobelt and even Galeforce. So Twisted Fate and Jhin are two examples of Champions that may benefit from the Mastery.