There are 3 new dungeons in 2.1 that you can run for your Myth. Not sure if CT will also give some Myth tomes, but that could even make 4. Then there are also the Beastman dailies which give tomes I think?

The ability to do the duty roulette as a group is honestly retarded. What's the point of adding a feature that (at least that's what I'd think it should do?) is supposed to help lowbies get dungeons faster as there's little reason to return there at high lvl when you fill the entire party with high lvls using the duty roulette?! This feature should add high lvls to the low lvl dungeons that are missing certain members. However, making a system that actively accomplishes this probably goes way beyond what SE is capable off it seems, so yeah, perhaps it's best that you roulette with 3 others because otherwise the system would let you queue up for Satasha for 2 hrs because nobody actually needs it at the moment.