"All-out Attacks"
The cave was created to reject teleportation so that the hateful people outside could not casually enter the caves to steal cubs.
It should also be near impossible to directly teleport to this secret lair without going through the portal in the underwater slum that the group visited before.
Entering was difficult, but leaving should not be too difficult.
After all, the cubs might also need to leave this space sooner or later and the mother monster should also facilitate the exits better than the entrance.
The difficulty in getting to meet the cub of the Loch Ness Monster was how to get into the secret lair and how to get into the cave without being killed by the guardian monsters.
After that, they also had to leave the cave alive with the cub!
Knowing this, the group gulped and looked at the long corridor in the cave full of guardian monsters and mutant plants that would not stay in their posts like before.