TrinityCore/TrinityCore — comment on commit 38dd1564690375c589d0fe246afc711c14c350d5
File:  line 0
By Discover-:

It's hard for me to understand you, I mean look at your reply.. If you don't even understand the NOT_REPEATABLE flag, try reading the wiki. That flag means this one line can't be repeated by the creature until reset.

So if I was setting the event_flags to not repeatable, how do you think you can do this quest if someone else did it just before you? (because apparently that's what you though, even if it's not going to work like that because whenever the player leaves combat the creature resets which means the same script will be called all over again on spellhit..)