Completed the first half with all 12 medals. It was a little tricky rng-wise but thankfuly my stamina was enough. You need to play a lot with your speed. In some stages you must have an all-slow squad, in others you need to interchange between a slow and a speedy squad, while the last one is pure luck/rng. It's not worth to farm the event stages XP-wise like the last event, so once you clear them, you better go and farm for manyus or whatever at the campaign stages. Only the last stage is noteworthy, giving about 6,500+ gold per run.

E2-1 is very easy enemy-wise but you need to make a set of two teams (3 in total with the helper). Make the first one very fast, while the second one has to be very slow, since it will go through the speed blocks. The helper squad should also be very fast. If you are lucky, either your fast or the helper squad will take the route to the bottom boss.

E2-2. 3 fast squads at the left camp, 2 slow ones at the right camp. It was a close call but my fast squads reached the bottom enemy just before one of the slow ones reached the flag. The hurricanes makes them fly.

E2-3 is quite interesting. I put my first team, who is very fast at about 600 speed, along with a helper team that has about the same speed, at the bottom starting point. The rest squads had between 280-350 speed and start at the top camp. All of them reached the flag at the same point.

E2-4 requires luck. It took me 5 tries to clear the circle enemies. Note that the boss in the center deals a lot of damage, so all of your squads must be strong enough to take him down (around 33k is good).