Question about the mechanics of indigon and damage snapshotting

Hello i've been theorycrafting lately around the item indigon and am wondering how this works in https://www.youtube.com/watch?v=IR7OuseFwao this video i see that the guy uses increased duration to basicly snapshot the highest indigon dmg increase at the end of a storm call duration i have been wondering if this works with other skills like for example orb of storms will the orb deal the increased damage over its full duration or only on the first cast the idea behind this is to use a channeling spell such as lightning tendrils to boost the orb of storms wich got a huge damage buff last patch and once the orb is down you keep casting lightning spells to abuse the damage increase from indigon

another question i have is how this actually works with herald of ice or thunder if you constantly use all your mana on an autobomber can you actually reach insane damage on your heralds?

excuse my bad english im not a native english speaker

thanks in advance to everyone who can answer this

as a result of snapshoting removal, damage of skills like orb of storms should update in real time.

heralds dont deal spell damage