Now go to the left and get rid of salamanders.
Cast Carpe Retractum on this draw-bridge and then again on these four draw-bridges.
Go to this place and jump down.
Cast Herbivicus charm (C) on the flower pads and the next Triwizard Shield is yours.
The last Triwizard Shield from this level you will find in the prefect's bathroom. So go there. Oh, the water is gone. Now jinx your fifth dragon statue and then use a cauldron to destroy the floor. You will see your Triwizard Shield.
To get the vanishing card, you have to run quickly to the left. You don't have time for killing salamanders. Quickly cast Carpe Retractum on the draw-bridge, run and you will catch the vanishing card. If not, simply press Esc, End Level and try again from the beginning.