Mabar event is *dramatically* different if you join a large group as a caster. Just prep fireball and lightning ball and you'll be an unstoppable killing machine. Seems the spawn rate is proportional to the number of people nearby, and whenever someone in your group kills something, the rewards are pretty much given to a random group member.
Oh, and coffee regens your sp at near enough the same rate you spend them.
Apparently there is a problem with the levels of the creatures that spawn being too low (you don't get collectibles often enough), so it's best NOT to use a lvl20+ character. Forum says:
Mabar Schedule
Greetings! Our engineers are very close to determining the root cause of the "too low level" spawn issue, as well as the performance issue with Epic Skeletons. Due to these issues, the Festival will end on Tuesday evening, November 6th. We'd like to weather the weekend to give people a chance to earn motes and upgrade items while our engineers keep working. The Epic Skeleton spawn rate will unfortunately remain low for the remainder of the festival.
Once we have our fixes in place, we will patch the festival during Update 16 on November 12th. With the updates applied, there will be an encore of the festival closer to the Thanksgiving holiday - while pumpkins are still fashionable before Festivult time rolls into town. We apologize for the inconvenience, and look forward to bringing Mabar back with the corrections.
Also a huge thank you to all players who submitted detailed bug reports, which have been invaluable to helping our team identify root cause of the spawn issue!