Emergency maintenance and an infinite amount of bad changes.
These recurring coffee breaks/'emergency maintenances' are really becoming tiresome, as is the Kabam fuelled hype surrounding entirely useless ripoff changes, most clearly manifested by the introduction of 6* moneygrabber champs, which further ruins the game.
Here is an idea: stop introducing new, made up, champs, one more ridiculous than the other, and focus first and foremost on making a bug free, enjoyable game. Make certain the game runs smoothly. THEN you can create more undesirable content and characters.