Prefect's bathroom part III Harry Potter GOF Guide

From this moment next sublevels will begin in this place. Go to the right, jinx your second tap and then go downstairs.

Here you will find your eighth mini-shield. Now lift a block with Wingardium Leviosa (C) and move it to this wall. Climb up and use a cauldron to destroy pipes on the left.

Again move the block to another wall and free your way to the Triwizard Shield.

Now go to this block, climb up and the next Triwizard Shield is yours.