The Executioner's word was guessed: Lily only gets 10 points!
Delenn, HeavyHalfMoonBlade and EirikDaude participated: They each get 15/3 = 5 points
Delenn solved the puzzle: She gets another 15 points for a total of 20 points.
If I may make a suggestion Great Mistress of the Dark. While it may make sense that the Executioner gets less points for making a puzzle in which the solution is not guessed, it may incentivise using hard to guess solutions which are also not very fun, e.g. __ => "OX". It may not be the best example, as once you have the vowel there are a limited number of words it can be, but I think you can understand my point. Just something to think about.