Have a look at these threads by @JekylandHyde
Just did a quick 942K Walk-Through Video for Epic in Avalon
Just did a quick 767K Walk-Through Video for Rare of Avalon - #2 by Sarah2
Just did a quick 1.2M Walk-Through Video for Legendary in Avalon
Teltoc Walk-Through videos 2nd place (Rare), 10th (Legendary) and 29th (Epic)
They show the process needed to score really highly in the challenge events.