From that start with 'e' and include 'dec', what's the largest word possible to derive?
extradecretal (13 letters)
How many words are possible to make from this list?
From this list of starting with 'e' that contain 'dec', there are 2 brilliant entries which are available overall.
What is the highest scoring word in Scrabble you could make?
The only option is is endecha which scores 13 points.