Here’s why pro players are using the Unsealed Spellbook rune on just about everyone

If you’ve watched any professional League of Legends region over the last couple of weeks, chances are you have seen quite a lot of Unsealed Spellbook. For most of us, that reside south of Diamond in solo queue, we probably don’t see that rune too often in our games, and we certainly don’t see it in bottom lane.

So, if you’re confused and trying to make sense of why it’s all over the LCS, don’t worry, we’re here to answer all your Unsealed Spellbook questions.

Why would pros need to switch Summoners in the first place?

The answer to this question started out fairly innocent. The rune made its first appearance in top lane and was used to help tanks survive the early game against more offensive counters. After all, if you take Ignite, teams will have to think twice before they dive you and you can switch back to Teleport before teamfights begin.

But, as the rune got more attention it started to get taken in more ridiculous places. The moment it became clear that the rune had gone too far was when it started to hit the bottom lane. Why switch Summoner Spell in bottom lane? Well, largely, to avoid missing one single minion wave.

Is that the only reason bottom laners take it?

Nope, there are actually a ton of reasons, but that’s the only one that has to do with swapping Summoner Spells. The other reason is to get further into the Inspiration Rune Tree, which allows them to grab Perfect Timing (free Stopwatch), Magical Footwear (free boots), and Cosmic Insight for a ton of cooldown reduction. And since almost everyone in a pro game has to have a Stopwatch anyway, it’s a win win.

So far everything we have talked about is directly related to maximizing gold value. From not missing a wave of minions to getting a boat load of free items and stats, it all means that the hyper carries that dominate the meta right now can enter the game with the biggest possible advantage — about 1500 gold in total. But there is one big in-game reason the pros are taking the Rune and it’s because of what it does to Summoner Spell cooldowns.

The cooldown reduction?

Yep, this part of the Rune took people a long time to figure out and it’s not exactly clear why. (Maybe it’s because people weren’t doing math quick enough?) Since it took professional analysts a couple months to figure this out, let’s go through the math that makes this Rune so good on marksmen and supports.

Unsealed Spellbook gives 25 percent CDR on summoner spells as a base. That means that Flash goes from a 300 second cooldown to a 225 second cooldown. Cosmic Insight gives an extra 5 percent, now Flash is up every 210 seconds. What this means for hyper carries — whose main disadvantage is supposed to be low mobility — is that their main escape is up about a minute and a half faster. Add in some Ionian boots — another 10 percent CDR for Summoner Spells — and suddenly Flash is up as often as Barrier, every 180 seconds.

That’s it? A Flash cooldown?

I mean, the cooldown on Heal goes down as well, but, yeah, that’s it. As they say you can’t put a price on safety. And if Flash is an AD Carry’s only means of escape, having it up almost twice as often — not to mention a support being able to Flash engage more often as well — means that teams can be comfortable taking fights more knowing their AD Carry can still get away.