Guild Wars 2

Looking for some tips and general help with invisible.
How long can mesmer stay invisible, say in SMC or keep?
Could also please provide build of how they do it?
Youtube vids i found were from 2015 and traits have changed since and perma invisible may not be possible.

Not much. You can have a “burst” stealth if you chain all your fast recast & stealth skills, but you’re on a big cooldown afterwards. So its not much use.

If you still wish to do so, here are a couple things that will help you out. Tho do not expect great improvement:

Weapons: Torch (obviously)
Skills: Decoy, Veil, Mimic, Mass Invisibility
Traits: Prismatic Understanding (Chaos), The Pledge (Illusion), Seize the Moment (Chrono).

Your Rotation would be something down the line like this:
The Prestige > Mass invisibility > Continuum split (use while casting MI) > wait for CS to revert MI > Mass Invisibility > Veil > Mimic > Decoy > Decoy > The Prestige. (End with huge cooldowns)