So how do I get the other two goblins out of here?

Hint 1 of 7:

Did you notice that the floorboards on the platform look a little loose?

Hint 2 of 7:

The one on the right side in the foreground is.

Hint 3 of 7:

Did you notice anything above the floorboard that could help you?

Hint 4 of 7:

The rocks up there also look a little loose.

Hint 5 of 7:

Try having Warrior hit one of those rocks.

Hint 6 of 7:

You'll notice that the rock makes the board spring up.  Wouldn't it be nice
if one of the goblins were standing on the board?

Hint 7 of 7:

Well, do it!  Put either Magician or Technician on the loose board and have
Warrior punch out the rocks above.  Repeat with the other goblin and go.