I cleared GR 150 on my SSF Necromancer in season 36. During this time I learned several valuable lessons. Since, I had to clear each individual level one by one, I made a lot of mistakes and learned a lot.
The most valuable lesson I learned was that facing the mobs you are training across the map will cause them to stand still and fight you.
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If you turn your back to the mobs and attack random mobs in front of you, even if your goal isn’t to do enough damage to kill the mobs in front of you, as long as your back is turned from the mobs you are training forward. They will follow you. This goes for elites of course.
It’s a really good way to group up three or more elites for example a Conduit Pylon or in the case of season 36 with Soul Shards, getting the Ring of Fire. Still going into season 37 it’s true that grouping up three or more elites will be good damage. Especially with Area Damage builds.
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Anyway if you try that, like just keep your back to the elites you want to train across the map and attack the mobs in front of you in the direction you are going, you’ll get the elites to follow, as they won’t stop to fight you like they do if you’re facing them and attacking them.
This completely changes the sweaty twitchy stutter-step play style. Although stutter-step is okay if you want to stay on the move while fighting, after everything is grouped up, to stutter-step to avoid taking damage. And stutter-step is not a good way to train mobs.
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My method is take a step and shoot, take a step and shoot, although you don’t need to move your mouse back and forth quickly like I see pro players doing, because you are facing the direction you are moving.
I guess it works with monsters also. 