Updated Singed Idea
Singed is definitely a champion you don't see everyday or even at all lately. I think a slight buff to his ult would change that. Here's what I'm thinking:
R (Insanity Potion) - Now gives him increased combat stats AND alters his abilities for a brief time. (Maybe 20 sec instead of currently 25 seconds)
(WHILE IN ULT) Passive - Probably stays the same for now.
Q (Poison Trail)- Sprays out poison in a circular cloud rotation around Singed that leaves behind a trail. (Thinking either four lines up,down,left,right that rotate in a circle clockwise around him OR like it says, just a small circle around him)
W (Mega Adhesive)- Enemy champions, and/or minions/monsters, that stand on Mega Adhesive for to long get ROOTED and take extra poison or acid damage over time. (I think W should have this overall instead of having to CURRENTLY land Fling onto Mega Adhesive to get a root effect)
E (Fling)- Some ideas, either A- Increase Distance/Damage. Or B- Increase damage/distance + Have a better choice of where to throw them. Maybe like a mini version of rumble ult for clicking the direction you'd like to throw someone. 360 degree options would be nice though.
Again just an idea to get this champion back in the game more because I'm sure Riot knows there are definitely some other champions that are falling behind or simply can't seem to stay relevant like Aatrox, Jarvin, Karthus, Mordekaiser, Quinn, Skarner, and a few others. Those are just what I personally don't see very often anymore but would love too.