Don't know if this has been suggested before but i would really like to be able to slay with my friends and work on long tasks together. Maybe open up a duo slayer shop with helpful rewards aswell.
I personally find slayer one of the most boring skills in the game; low exp rates, no rewarding tasks and just a tremendous grind. However I believe that this will change when you have someone you can share your experience with; both working towards a common goal. Support.
I'd love to see more functions to the Slayer Skill, it'd be a lot more fun doing Slayer with your friends. I'd also love to see the block task feature added in, seeing as I'm a super donator and I can skip for free, it really does make finding the tasks you want to do really teadious