How do I see which boss will spawn?

In the lobby, open the console and type getall kfgamereplicationinfo bossindex. An index of 0 means Hans Volter.

What if the wrong boss is selected?

Type RestartLevel in the console to reload the map quickly and check the boss index again.

Does this only work in the event?

No. It works in any game and in solo or multiplayer, so you can learn the end boss before the match.

KF2 Last Hans Standing: Force the Hans Boss Spawn

The 2023 Halloween event Last Hans Standing asked players to kill Hans Volter on five different maps (the "Hans Spawn Hunt" challenge). Because the final boss is random, the author spent over 30 fights and saw Hans only once. This short trick removes the luck.

How it works

Enter a game, solo or multiplayer, and stay in the lobby.
Open the console and type getall kfgamereplicationinfo bossindex.
Read the result. An index of 0 means Hans Volter will be the boss.
If a different boss is selected, type RestartLevel in the console. The level restarts quickly and the boss is rolled again; repeat until the index is 0.

This also helps outside the event: you know which boss will show up at the end of the match.

For more event help see Castle Volter trophy room walkthrough and console commands.

FAQ

How do I see which boss will spawn?: In the lobby, open the console and type getall kfgamereplicationinfo bossindex. An index of 0 means Hans Volter.
What if the wrong boss is selected?: Type RestartLevel in the console to reload the map quickly and check the boss index again.
Does this only work in the event?: No. It works in any game and in solo or multiplayer, so you can learn the end boss before the match.