So for a while now, the meta for most builds has involved the Purple Rain loop. Cast PR, spam QuickCast skills while using Essence Orb to buff yourself into high heaven and crippling your enemy into the ground. This is obviously not healthy for the game, as the existence of the strategy greatly narrows design space for encounters and bosses, as the staff always have to ask, "How can we make this challenging/interesting to those using the PR loop while not locking out those that don't abuse it?"
A nerf is obviously needed, and I'd like to put this suggestion out here while also possibly solving another problem. Endurance as a stat is pretty much only used by Backlash builds, because it's generally accepted that Luck is better in almost all other scenarios. If you're offensive, it gives added accuracy and Lucky Strikes, and if you're defensive, it gives you additional blocking and bonuses on all status rolls. And for both approaches, it gives you the first turn in a fight, reducing damage and allowing a safe setup for the PR Loop.
My proposed fix for both the PR Loop and END is simple: Place a global limit on the number of QuickCast Skills a player can use each turn, based on their Endurance. This will give both nerf the PR Loop by preventing players from spamming as many QC skills in the loop as their resources allow before resetting them, and give Endurance another use outside of Backlash builds. This will both open up design space again for developing encounters, and it will open up build variety for players.