Is there a trick to beating Drox?

I haven’t Since Conquerors of the Atlas’ release, I’ve never figured out how to deal with Drox. The first few fights are fairly easy, but by the fourth time around, he becomes too spongy to beat. Essentially, the moment I can take down one or two of his Vexillum Immortalis flags, he’s already dropping in replacements, giving me a couple of seconds at most to actually hit him — if he decides to stay in an uncovered area and I can reach him without getting a flagpole through my head.

Over the recent leagues, I’ve tried several builds, including physical, elemental, and chaos damage, and finally, minions. The other Conquerors can get tricky, but at least they’re beatable. The most upsetting part is that my current searches seem bring two kinds of results: either he’s nearly unbeatable, or he’s the easiest of the four.

Is there an obvious trick I’m missing? Do I need to use a particular damage type? Do I simply need more damage?