At the end of the game...

[xureus]

I got the head of this fellow who was hung up to the ceiling at the end of the game (he told me to cut it off after giving him the tonic).
What am I supposed to do with it?

I just ran to the Altar room and ended the game but I didn't have to use it. So what is it for?

[ymgve]

Spoiler below!

In the final room where Alexander is - wait for a few minutes. You'll understand what you have to do.

[xureus]

thx, I'll try that out

EDIT: I tried it out now, thanks again! Now I saw 3 different endings of the game.