One question, answered from the books

How do I track the enemy jungler?

Tracking is not warding, it is arithmetic. You need three inputs: where he started, how fast his champion clears, and what his CS number says he has taken. His start plus his clear speed is a prediction, and every time he shows on the map you update it. Say it out loud if you have to: red start, three camps by 1:55, bot-side Scuttle at 3:15. If he shows top at 3:05, the entire bot side of the map just became yours for ninety seconds. The players who feel like they have map hacks are doing this, nothing more.

The decision, as a picture

What it looks like in a real game

Their Kha'Zix started red on the top side. It is 3:05 and he has not shown. He is not missing, he is finishing his clear low, near bot-side Scuttle. You do not need a ward to know that, you need his start and a clock. Path your next ninety seconds like the bot half of the map belongs to him and the top half belongs to you.

The concept: The first read

The Perceptive Jungler builds the whole skill from this loop: start, speed, CS, update. Its companion rule keeps the read honest: hold it loosely, and never die testing it.

"The more you understand jungle openers and clear routes, the more a single glimpse of the enemy jungler turns into a full prediction of his movement."

"You build it from imperfect information, you hold it loosely, and you correct it the moment something contradicts it."