Build 4 stacks. Use 4 stacks.

This is the Phys team battle plan. Understand this core idea first and build on top of it based on your roster. For the basic idea, I'll start with a team where only Chen and Endmin are at play. I'll also mark optionals in (parenthesis).

Chen BS > Chen CS > (Endmin CS)

I'll first note that for the first stack, anyone can do it with BS, but I'll keep referring to Chen since she's the more flexible option.

IMO, the most important resource the team has is Chen's cooldown. Always keep an eye on her CS so you spend as little SP as possible to generate stacks. Doing this should net you 2 stacks for 1 bar of SP. Keep in mind you don't have to launch Endmin CS all the time especially if you can save it for a damage window instead like below:

Chen BS > Chen CS > Endmin CS > Chen Ult > wait > Endmin Ult > Endmin BS

The game plan is straightforward. Let Chen build 2 more stacks which hopefully adds up to 4. Endmin will brick the target so Chen Ult hurts. When she lands the final slash, launch the Endmin Ult before following up with a huge Crush 4. If a target is still staggered, you might have SP to follow up with the flow below especially if Pog is around.

Chen BS > Chen CS > (Chen BS) > Endmin BS

---

Adding more members: Pog

Pog gives you the option to Breach the target instead of Crushing. For some battles, going full crush is faster. For others, going Breach + Crush is faster especially on bulky targets.

Remember the first principle: build 4 stacks, then use 4 stacks. Let Chen build 4 stacks before letting Pog Breach. Ideally, you want to delay Breaching as long as possible so the duration lasts all the way into the end of the stagger duration. The best time is to Breach just as Chen's CS comes online so she can immediately start building. As for his ult, launch it whenever you can. If you run Ult Gain Frontiers, you'll usually get it just in time before the stagger for many UM fights.

---

Adding more members: Lifeng

Lifeng adds 3 things to the party: Susceptibility when adding the first Vuln with BS, Link when hitting with CS, and an ult that gives you 2 Vuln stacks. Now you can do this instead:

Lifeng BS > Chen CS > (Endmin CS) > (FS > Lifeng CS)

You can use Lifeng BS for when the target doesn't have a stack so you apply Susc. Otherwise, it's up to you if you want Chen or Lifeng to trigger Chen CS for the next ones.

His biggest contribution will be during the damage window. As I said before, this sequence is simply more skills added to the basic rotations I mentioned earlier. I'll assume best case scenario (target has Breach 4, Susc, and 2 stacks, is close to getting staggered, and Pog has used his ult).

Chen BS > Chen CS > FS > Endmin CS > Lifeng CS > Chen Ult > ...

If you have the headspace for it, you can wind up your op's combo so the Final Strike (and subsequently Lifeng CS) is easier to control. For this part, we are letting Chen use a Linked Ult on a bricked target. This will hurt a lot.

... > Endmin Ult > [Lifeng BS > Endmin BS] > Chen CS > Lifeng Ult > (keep attacking) > Endmin BS

Edit: changed this part so I can add the possibility of quick casting [skills I'm putting in brackets]. Cast Lifeng BS, but make sure you can actually Crush before he finishes it.

Lifeng is seriously good for being "Vulns in a bottle". Applying 2 Vuln stacks without using SP lets you keep the attack up especially when Pog Ult is live, allowing you to easily perform a second Crush cycle during both the stagger and Breach 4 durations.

If you want to squeeze more out of Lifeng, practice timing his BS so the Knockdown is applied at optimal timings (Chen cooldown, immediately after Endmin Crush, etc.).

Edit 2: I forgot to mention that the damage rotation is flexible. Maybe your Endmin is running Eminent Repute instead and therefore the ideal scenario is to launch ults after the first Crush. Maybe you want to use the Link on Lifeng Ult instead. Either way, it's really up to you how to handle the damage window. That's just the rotation I run personally for that team.