ive tried to use pillar of nirn several times and stopped using it because its very underwhelming to me

ive also had problems with the proc actually hitting things sometimes because it is a very small delayed hit aoe (so its not good for dealing with large mobs either), and if it misses the target, thats 10 solid sec of it doing absolutely nothing

ive never actually tried using unfathomable darkness but that is definitely more of a single target set than an aoe set

one stam set i enjoy focused on dot is unleashed terror, its very easy to apply, cooldown is per target, pretty good dot + reapplies hemorrhaging status with each tick (more dot, and if applicable minor mangle for -10% max hp debuff)

edit to add: a DoT centric build im using right now is unleashed terror + deadly + 2h maelstrom front bar and 2h vateshran back bar, vateshran back bar adds the buff to momentum to give me up to 300 more dmg, 2h maelstrom front bar + unleashed is applied when i use stampede (in an aoe too mind you) and deadly is boosting all the DoTs (and since its a stamplar also boosting jabs)

PON is a better set for trials mobs than dungeon mobs but if you aren’t speed running PON works well enough in vet dungeons. The trick is to front bar it, wait until the tank collects several adds and then swap to you front, there will be a delay before the proc hits but it will likely finish off anything inside it’s radius.

How I use it on my warden is to lead in with shalks (front bar) barswap to backbar then stampede, barbed trap, winters revenge and then barswap again into 3x carve (I run double 2H) and that usually kills whatever mob is there before I even get my growing swarm and birds out.