Well, the event maps are fairly easy, they just have some weird speed requirements needed to 3-medal with the web and tornado panels. Also the 50 stamina last map only gives 160 exp, so it's kind of a pain to keep running it.
EDIT: Took screenshots of the last 2 maps since I needed to run them again in case others want to plan before going in:
The nodes are really weak, so focusing on speed is more important that power. For example, used this for map 3:
with team 1 and helper on the bottom and the rest on the middle node. The enemies can't even scratch most evo'd or high level characters.