What made you decide to add cleansable effects (besides Cleanse) to Morde's ult? It doesn't seem like a CC ability, and QSS no longer removes Debuffs. Just curious!
Also another thing, new Morde has very little sustain compared to old Morde. Was this one of his old issues, since mixing together lots of sustain and shielding might become problematic?
We were primarily looking to make sure that the ult wasn't a guaranteed long-duration banish. Without the ability to cleanse it, it makes the Morde player's choice around who to ult a lot less interesting. You basically would just build tanky and R the highest threat target and put them into a long time-out while your teams teamfight.
With the ability to get out of it, it motivates the Morde player to build offense so they are more than just a tanky CC bot, and to think more about who to ult, and why, and when.