League of Legends (LoL) Question: Why don't jungles take unsealed spellbook?

Hey Ronykon, thanks for the shoutout! Unsealed Spellbook is pretty strong, but you have to sacrifice a "real" keystone for the sake of your summoner spells. Smite is a pretty low-priority spell compared to other summoners. You can store two charges and the cooldown is only 75 seconds, so you can have it up for combat and objectives even without the CDR. In terms of clear, the keystone only knocks 19 seconds off the cooldown, which isn't going to make or break your early game.

A lower cooldown on Flash would be nice on some junglers, but in general it's currently not considered to be worth losing a combat keystone. The only jungler I've seen the keystone used on is Ivern, but even in his case, Summon Aery is more popular and has a higher win rate.

Meta Junglers typically don't take it because there's better benefit for them in other Runes. Off Meta Junglers like mages or ADC's typically will take it for the big Smite cooldown so they can clear the jungle easier in the early game. I've also seen some master Yi's take it so they can swap Smite for TP in the Late Game to backdoor, but I've only seen that 3-4 times. Meta junglers just don't need the clear speed.

TP is great late game, but if you swap out smite do the true damage to monsters reset to 0 or does it retain its value once you switch back to smite? (Not sure if i need to create a new thread for this question :/)