In Destiny 2: Season of the Undying, Vex show up in three different locations around the Moon directly after a Public Event: Archer’s Line, The Hellmouth, and Anchor of Light. You’ll need to beat back a ton of Vex and their Gate Lord bosses to close the portals. But there’s a chance to summon another boss for even better loot: a Vex Overlord.
Unfortunately, summoning the Vex Overlord is a completely random chance. After playing dozens of Invasions ourselves, killing Vex Hydras, and looking for secret enemies, we’ve come to the conclusion that there’s nothing you can do to influence the Overlord’s spawn. We’ll update this guide if we learn a more concrete way to spawn it, but for now you just need to participate in as many Invasions as you can find if you want a powerful piece of loot.
If you haven’t seen an Overlord yet, here’s how you’ll know if you managed to spawn one. After you kill the third and final Gate Lord, you’ll get the normal notification that the Vex are leaving the area. But the final chest won’t spawn and it will say a Vex Overlord has launched an attack. Look for the giant Hydra — it’s hard to miss — and give it all you’ve got. This boss has a lot of health, but it will drop a Powerful item for you twice per character per week.
If you want a special Triumph for the Season of the Undying, summon and defeat a Vex Overlord in each of the three zones on the Moon.