I don't know the exact number you're looking for but yes, after a good amount of riddles you'll unlock the third mission. I'm still trying to unlock the fourth myself, I'm really hoping I don't need all of the trophies.
XBox live GT: Gritzy85 "Man can overcome anything except a succession of ordinary days." - Goethe
i got 390 Riddler's Trophy & .... but where is the last hostage ? lol and where is the last 10 riddler's objectives ? 75% of Enigma completed & 100% of the game and 76% overall and all the other side quests are closed & completed
Finall got the 3rd one, its at 160 secrets found. I'm kind of stuck in the challenge as i am at the part with the Line Launcher but when I do the tight rope walk and try and glide past the spike wheel i keep dying, itheres gotta be another way.