The Citadel of Chaos

You draw your sword and hack at the tentacle.
The tentacle will not fight back as will a normal creature,
but instead is trying to drag you into a large hole in the ground which is opening around its base.

If it succeeds in dragging you into its lair.

If you do defeat it, you can peel the tentacle off your leg

and proceed to the main entrance to the Black Tower.