The Miasmic - Heavy Striker has a high chance to put up it's Miasma Shield at any point, but is much much more likely once it reaches 50% or below.
The Miasmic - Lightfoot Rover instead uses this HP check to manage its Drones.
Both robots have an Anti-Interrupt Level of 3, meaning any attack with an Interrupt Level of 4 or higher will Interrupt their animations. Attacks with Interrupt Level 4 or higher usually consist of Dodge Counters, EX specials, Chain Attacks, Ultimates and Defensive Assists. Some attacks like Zhao's Charged Attack and Harumasa's Dash Attacks also have an Interrupt Level of 4.

The first of the robots that reaches 50% HP or less will gain 80% DMG Reduction and automatically execute itself after 5 seconds. At this point, a flag is sent to the other robot. This flag forcefully sets the enemy's Stunned State to Normal (removes the Stun), removes any execution flag so they don't both die, and forces it to use a specific Attack, called Attack #9. During this attack, it will recover 40% HP and change its attack pattern, attempting to merge with the other robot.

Successfully interrupting the merge interrupts the HP recovery, making it a lot quicker to clear the first wave. To be specific, the 40% heal happens 122 frames (about 2 seconds) after triggering Attack #9, so there is still time to Interrupt it during the start of the animation.

The intended robot to get to 50% HP first is Lightfoot Rover. If Lightfoot Rover dies from the execute, points are gained as normal. Currently Heavy Striker dying by this execute instead seems to be bugged, deleting the enemy but not granting any points for it's death.

When Heavy Striker puts up its Miasma Shield, its Anti-Interrupt Level increases from 3 to 5 for all attacks except Chain Attacks, Ultimates and Defensive Assists. If the Miasma Shield does go up, the attack needs to have an Interrupt Level of 6 or above instead of 4, which are a lot harder to come across and usually is only found on Ultimates or Defensive Assists (which bypass the increased Anti Interrupt Level anyways).

- Get Miasma - Lightfoot Rover to 50% HP first. You can attack both at the same time but make sure the one with floating drones hits 50% HP first.
- At this point, Lightfoot Rover's execute timer will start. Use high Interrupt Level attacks to keep Heavy Striker Interrupted until Lightfoot Rover's execute takes place.
- After 5 seconds, Lightfoot Rover will die, leaving Heavy Striker with low HP and can be killed easily.

Zenless Zone Zero 3.0: 10 Minutes of Deep-Dive Gameplay

Check out ten minutes of in-depth gameplay provided by the development team for the 3.0 version of Zenless Zone Zero. This gameplay shows off Roscaelifer’s rich environmental ecology and new interactive elements, including a new Skybus transit system, a more intricate exploration experience, and expanded Bangboo gameplay mechanics. Additionally, you'll also see a brand-new combat experience featuring the gameplay of Pyrois (the long-awaited combat avatar of Phaethon), alongside new Agents Velina (ZZZ's very first Wind-attribute Agent) and Norma.