Events like these are about as restrictive as they are fun.
COME PLAY LEAGUE AND EARN REWARDS.
But you can only play this role. On this game mode. And you have X amount of time to reach this goal. And then you have to wait a whole week for the next goal to become available.
Seriously guys. Some of us have assignments and study to do. Don't make us choose between assignments and getting LE rewards.
Please make the next event less restrictive. You didn't even allow Jungle Monsters to count toward the 500 minions goal.