Or, you know... How about making something so people didn't WANT to leave? Make Mentors earn 5 roulette credits for a dungeon and 10 for successful EX primal kill, so they can stop fishing quick 2 minute guildhests which give... just think... the same credit as 40 minute wipefest, which actually most of the time gives no credit at all because of duty abandoning. For those who want only mentor mount its counter productive to stay... What's the incentive? (And no, teaching is not enough motivation or them).