In a dream I recently had, I played an imaginary champion who's niche was to be as _simple_ as possible. Even simpler than Nunu. To make it weird, the champion's name was simply "Duck", and surprisingly was literally just a duck.
Here were an example of some of his abilities:
Duck gains movement speed after being hit by an enemy ability after a certain period of time.
Q (Feather Toss)
Duck throws a feather at an enemy unit, dealing magic damage.
W (Birds of a Feather)
(Passive) Duck and his allies gain a shield whenever they are near each other.
Duck targets an enemy unit, slowing them and increasing magic damage taken by that target.
Duck spreads his wings, ignoring unit collision and gaining movement speed until hit by an enemy or ability is cancelled.
Of course I don't remember all the details but it was something like this. This gave me the idea to start this thread, with the goal of designing the most simple champion possible. The ideas are limitless. If you have any ideas for simple abilities, post them here.