If you need to use Engulfing or another option, you can just cut Camo for it, for Proxy, or Spell Symmetry.
You want to only press Stagger once, to apply the stomp AoE debuff. In an ideal world, other DKs in your group will do it too and the trash will have 3x Stagger stack, perfect for arc beams.
In situations where there is only 1 add left, and the group starts running already, you want to use stagger from range while starting to run already.
If you are using the White Cloak, you can use RaT and use it as your speed source, but be aware that it will be hard to sustain magwise.
If you are using Maelstrom bow/Master bow on bosses, you will want to use the Endless hail morph.
Your rotation should look like :
Prebuff FoO/Cloak if you have/Destro if you have; Hail/Eruption while running in.
If you are on Engulfing, press it there, otherwise Talons > Deep Breath > Stagger;
Ideally want to press Talons and Deep Breath only once then spam Spin2win until the pack is over.
Don't underestimate the range of Spin2win and your LA, you can start moving at the same time as arcanists and eventually use Stagger from far if needed.
Use additional Light pieces if your group doesnt have Alkosh in trash/you don't trust your alkosh DD.
Use Order's Wrath if your group doesn't have good Force/Brittle/Catalyst uptime - or in 4 man.
If you plan on not using the elden ring set, swap the non-poison glyph for an Absorb Stamina one.
It's nice to have an ulti setup with Acuity, inferno backbar, destro ult etc. for when you are planning on dropping your ult, the difference in logs will be noticeable.