This bug has two parts, that can be triggered consistently and has no secondary conditions other than Kled having his W.
1)If You auto attack while Kled's W is just coming back from off cooldown, kled will only have 3 auto attacks with bonus attack speed, and no 4th auto attack with bonus damage.
Now here is where this bug gets weird.
2) do the exact thing as step 1, instead of Kled having only 3 auto attacks with bonus attack speed and no 4th auto, you have 1 normal auto with bonus AS, but you have 2 autos with bonus AS and with bonus damage as well. In other words: if you do this bug twice in a row, your next W deals 1 regular auto and 2 empowered auto attacks that play the animation and deal the bonus damage.
This bug can be abused through 'buffering' the first W on a minion wave and then going to a trade with your second W to deal a lot more damage in a shorter window.
Gamechanging: Potentially, as your first W bug can be the difference between securing a kill or not having the damage to finish it.
Consistent: 100%, requires a bit of practice however.
Abusable: Yes, can "cheat" a higher DPS in a trade.