The Maven forces you to Path of exile currency pick different maps, so she can transfer those slain map bosses inside her Crucible.

For example, if you run Crimson Temple and defeat the Sanguine Siren (the map boss) while the Maven's influence is active, you'll see a progress bar in your map device under the Maven's influence. Once you fill it up, you'll get a Maven's Invitation. Put the invitation in the map device, and then it should take you to the Maven's Crucible.

In the Maven's Crucible, you'll fight all the map bosses you have defeated. These bosses fight you in pairs, but if you don't defeat them fast enough, the other bosses will start to join the fight. After finishing the encounter, you'll get some amazing loot (all the bosses combined) and some Crescent Splinters.

Ten Crescent Splinters will instantly turn into the Maven's Writ, which is then used to fight the Maven.

fter the first Maven's Invitation from the initial objective, you won't get the invitation drop anymore. Instead, you'll just need to talk to Kirac to POE orbs activate the Maven's Invitation.