Crabbe and Goyle
Your main task is to create the Polyjuice Potion. The cauldron can be found on the right side. Head towards the left corner of the room, where you will find the broom #1. Use it (WL) to knock down the valve from the shelf and attach it to the machine #2. Turn the valve (WL). You will break down the shelf and knock down the cherries - throw them into the cauldron.
Jump onto the toilet bowl and use (WL) to turn the valve #1 - it will lift you up. Jump two bowls left, closing the first one which was in the air in the beginning #2.
The toilet next door will explode. Place the pipe piece above the container on the left #1 and water will start falling into it. Once the flower blooms, destroy it (WL), afterwards assemble (WL) a freshener from the scattered bricks and place it in the toilet filled with bad scent. Pick up the apple lying in the middle #2 and throw it into the cauldron.
Use (WL) to pick up hair from the heads of both sleeping students #1 and you will get the last ingredient of your potions - drink it. You will end up in the Slytherin Dungeon - go down. Use the (LS) on the Devil's Snare on the right #2 and (WL) on the chest. Put the bricks together (WL).
A snake will appear and start to lean out of the four sewages. You have to hit it four times - as he leans out of each sewer #1. You will gain a piece of armour - put it back together using (WL) #2.
Now you can head to the entrance #1 - you will be let into Slytherin Common Room. Go right and you will find a spherical aquarium #2. Use (WL) on it.
Once the fish creeps to the second aquarium (with a skull), once more use the (WL) on the fish #1. Act similarly with the skull which got to the surface - use (WL) on it twice, first to get it out of the water and then to put the eyes #2 into the snake.
You begin in the Bathroom Hallway (M1.4) #1. Head right to the very end and follow Moaning Myrtle into the bathroom #2.
Tom Riddle's Diary
Moaning Myrtle will start throwing stuff at you, while hiding inside one of the cabins #1. Use (WL) to throw back the items and open the doors. Once you get to Myrtle, attack her with magic #2. You have to do this four times in total.
Your first task is to create the Strengthening Potion. Use (WL) on the bookshelf right next to the location entrance #1 - you will get the hand. Jump on the three buttons on the ground #2 and platforms will come out of the wall.
Firstly go right, take the circle off the wall (WL) #1 and then jump onto the button - the platforms will stop moving back into the wall. Jump to the left side and use magic on the pot - weapons will come out of it #2. Collect another ingredient and put it into the cauldron.
Jump onto the platforms once again, move right and use magic to destroy the chest #1. Finish the potion. Now you have to get to the chain. Chase away the Devil's Snare (LS) which are holding the wardrobe #2 and then use (WL) to attach the door. Go inside and put on the earmuffs.
Grab the Mandrake and break the glass #1 with the chain behind it. Drink the Strengthening Potion and pull the chain. Don't forget to put the shouter into the pot on the left. A few brick will appear. Arrange them so that you can get past the little pit #2.
Move right and use (IM) to get rid of the Cornish pixies holding two bricks #1. Place them one onto another to create a passage #2.
Return to the beginning, while creating a bit of the Strengthening Potion on your way. Jump onto the platforms and then head to the right end. Another chain awaits you there #1. Jump down and move on right to the next room. You will get to a staircase, which isn't facing the right direction. There's a button at the back - jump on it and the staircase will move #2.
Use magic on the painting - the wizard will give you a circle, which you should then mount (WL) #1 and jump onto it - the second staircase will change position. Use (WL) on the valve #2, so that the second character can move on through the rotating bookcase. Afterwards switch to the second character and also use (WL) on the valve.
Use (WL) twice on the banner on the left and you will create a small trampoline #1. Jump onto it and then to the rocky ledge. Use (LS) to chase away the Devil's Snare, which will leave behind a couple bricks #2.
Place the bricks on the wall using (WL) and you will create two platforms #1, thanks to which you will be able to jump upstairs. Push away the two columns #2 using (WL).
You begin at the Bathroom Hallway (M1.4) #1. Follow Nearly Headless Nick towards Hagrid's Hut (M3.24) #2.
Follow the Spiders
A while after the mission begins, you will be attacked by a hornet. Get rid of the nest #1. Dig up the machine from the ground using (WL), jump onto it and head towards the ledge #2.
Destroy the grass by the tree, create a cloud #1 from the round blocks (WL) and move it right, above the withered tree. Go up the ladder with the other characters and switch to Fang. Dig a bit by the tree on the right, causing it to collapse and create a passage #2.
You will find two brooms on the bridge #1. Get rid of the Devil's Snare using (LS) and then cast (WL) on the brooms. Jump onto the brooms and fly to the other side of the lake, destroying the nest above the water. On the second bridge, connect the bricks creating a staircase #2, so that the other characters can get out of the water.
Once the pixies destroy the bridge, a ladder will be made - climb up #1. Destroy another nest and then eliminate the pixies from the tree using (IM) #2.
Switch to Fang and dig up a hole #1. You will have to fight a large spider. Apart from him, small ones will also attack you - try to dodge the boss' attacks and shoot the small ones. Purple spiders don't explode - they flip over. Once they do, use (WL) on the twice to raise them, twist and throw #2. Do this three times.
The next task is very simple - drive the car all the way down, running away from the spider #1. If you drive too slow or stay close to the spider for too long, you'll get caught #2.
You will begin in the Main Hallway (M1.1) #1. Head to the Defense Against the Dark Arts Classroom (M4.49) #2.
Approach the painting in the left part of the bathroom and use magic on it #1. The wizard will destroy the tiles blocking the entrance to the pipe. Switch to Ron and enter the tunnel with Scabbers. After getting to around the middle, switch to another character and use (WL) to unlock the further path. Return to Scabbers, press the red button and Devil's Snare will appear in the next cabin #2. Switch to another character once again and use (LS) on them.
Fit the missing tunnel piece using (WL) and lower the flush to unblock the passage (WL) #1. Switch to Scabbers and move on, pressing the red button. Head to the cabinet and chase out the frog using (WL) #2.
Connect the bricks into a plunger, fitted with a chair (WL) #1. Get on it and jump into the clogged toilet. You will get more blocks - connect them all (WL) #2.
Talk with the snake #1 and jump down. Head left and use the plunger (WL) on the creature which has appeared #2.
Use the bricks left and create a platform (WL). After you get on it, the second character will lift you up #1. Go to the very end and put together the skeleton, which will start fishing and will catch the creature. This time it will be blowing upwards. Jump to the ledge on the right #2, assemble the bricks and create a bridge (WL).
Summon the snake #1 using (WL), jump into his mouth and enter the pipe. You will bump into the Basilisk. Run to the pile of rocks #2 and wait until the rays coming out of his eyes stop shining - jump off and the Basilisk will hit the rocks. Repeat this with the other two piles.
Each time you will find one ingredient of the Strengthening Potion behind the rocks. You will receive another one after speaking with the snake #1. To get the next one, use (LS) on the Devil's Snare #2 and then (WL) on the box.
The last one can be found in the chest - use (WL) on it and then smash up the snake #1. After drinking the Strengthening Potion, approach the chain on the left and pull it #2.
Free the Phoenix, which will poke out the Basilisk's eyes. Now attack the Basilisk with magic #1. Attach the chains of the mechanism on the left (WL) #2 and jump inside.
You will end up near the enemy. Use (WL) on the Sorting Hat #1 and it will spit out a large sword. Wait for the Basilisk to stop attacking and quickly jump into the tunnel. Grab the sword with (WL) and aim it at the Basilisk #2.