Ahri's Ultimate With Charge Counters
Ahri is a pretty good champ already. She get true damage, auto targeting spells (for better, for worse), hard CC (DFG damage boost), and mobility.
Ahri's, ultimate (Spirit Rush) gives her a quick burst of mobility; but what if it was on a charge system like Akali? Moreover, Ahri's ultimate would still function the same except the cooldown is on a charge system. Details: three charges, each on a 90/75/60 second cooldown (or so); upon kill or assist, a charge is restored.
I think that would be an interesting change to consider. I believe it would improve her kit, making her more assassin-like (a fox is both cunning and hard to catch) while still retaining the core of her mage-like charm (pun intended). This change would not make Ahri overpowered because she has a relatively small mana pool (especially in the current meta of building her), ergo abilities must be used sparingly to allow for her bursts of slaughter (R E Q W AA R ...). Plus she is a squishy mage; if focused, then she goes pop real fast (gib fest).