How do you acquire Bond of Vigor

How does one get "bond of vigor?" I'm trying to figure out what u get each episode in season 4. Ep1 - ? | Ep2 - Bond of life? | Ep3 - beetle mount | Ep4 - Bond of vigor.I completed the story in ep3 and got nothing extra w/ masteries so i guess it was just the beetle mount and the 3 base masteries (wrecking ball, barrier smash, big air).I'm curious and about to find out i guess (doing story ep4 right now) if "Bond of Vigor" is tied to finishing Season 4 episode 4 story?But i wonder if i have to activate everything by doing ep1 first???? idk

If it isn't unlocked for you yet, just do the first chapter of ep4.episode 1 is volatile magic collecting ability.

Episode 4 - A Star To Guide Us : Chapter 1 - A Shattered Nation | Chapter 2 - Chaos Theory | neither of these 2 chapters unlocked bond of vigor :(

edit : hmm it might be further along in the story with Aurene?? https://wiki.guildwars2.com/wiki/Bond_ofVigor(mastery)

double edit: Doh, just noticed an entirely different track in masteries as i was completing Legacy (story mission) - "Crystal Champion" its not in the beetle track line, its beneath it. :/ and you have to train "volatile magics" & "bond of life" before you get "bond of vigor" :(

S4 Ep1 (Daybreak), unlocks the Crystal Champion Mastery Track, which contains Bond of Vigor.