Best tagging build?
Chrono improves it. Also wells are ridiculous depending on the spawn and concentration of enemies.
The short answer is Alacrity makes spamming easy.
The downside is you still require a lot of effort compared to Revenant Hammer, Engineer Flamethrower, or Guardian Staff.
GS with fire sigil, MoP, zerker/assassin stats, Sw+F as your second set (sword for cleaving at Invulnerable spawns etc., focus for getting from place to place and grouping mobs)
Traits don’t matter that much, take your pick out of Domination(+ %dmg), Dueling(crit, MoP charges), Illusions(iZerker+shatter cdr), Chronomancer(wells, movespeed, alacrity). If running chrono add damaging wells and Alacrity, as much as you can.
The downside of chrono for tagging is that wells have substantial cooldowns (MoP and GS do not!), and spamming shatters/wells to maintain alacrity wastes those skills when you’re not in range to tag something with them.
Action Camera combined with “allow skill retarget” helps a lot for “sweeping” your gs auto over a constant stream of mobs like when farming the halloween labyrinth, for wave spawns like Ulgoth pre and Orr events you want to stand where they become vulnerable swinging your 1H sword, and drop wells/instant-cast illusions+shatters/MoP the instant that blue icon vanishes. For spawns that can be hurt before they’re visible don’t bother bringing any extra illusion generation, this is where chrono really outshines the rest with pulsing wells.
Blink, additional movespeed and mantras can prove helpful when you need to move a lot and/or enemies pack a lot of cc/impairing conditions.