Solutions for Act III Scene 2 - Li Ven Se Tt Le

Warning: Spoiler for the fourth Harry Potter book below

The title and the layout of the puzzle both hint at the game "Seven Little Words", in which one needs to reconstruct a pool of letter tiles to form, well, seven little words according to given clues. This puzzle employs the same mechanic — but there are no clues! However, since we want to form seven words, our best guess is that we want to form sets of seven with the letters. Playing around with the tiles shows that this is indeed the case, and we get:

SetWords formedUnused tiles
Scale degreestonic supertonic mediant subdominant dominant submediant leadingnoteCAM PHY
Chinese chess piecesadvisor cannon chariot elephant general horse soldierEZY GUA
Aspects of the Seven (Game of Thrones)father mother maiden crone warriot smith strangerALI OPE
SI base unitsampere candela kelvin kilogram metre mole secondLUM OTH
Rainbow coloursred orange yellow green blue indigo violetSL NK
Harry Potter DADA teachersquirrell lockhart lupin crouch umbridge snape carrowEUR SNE
Classical planetssun mercury venus moon mars jupiter saturnDAT OLE

The next step is to put together the unused pieces to form words which are also part of seven-word sets:

SNEEZYDisney dwarfs
PHYLUMMajor taxonomic ranks
SLOTHDeadly sins
GUACAMOLESeven layer dip ingredients
DATALINKLayers of the OSI model

Note that we have only formed six words. A quick search will reveal that each of these words appears in the xkcd comic "Seven", suggesting that the answer is the seventh, missing COLOSSUS OF RHODES.

Design notes:

It's possible to solve this puzzle with only about 3 or 4 sets completed. This was simply because the gap between solving most sets and solving all the sets was too large, so the puzzle was simplified accordingly.

The answer is: colossusofrhodes