This champion is designed to be a high risk, high reward ranged ADC champion that hasn't been done in league yet. This is down to a "chance" to deal bonus damage due to the passive. The percentages are all a bonus of the FULL attack damage.
Passive: This champion has a 1 in 5 chance to do a bonus 15% attack damage on hit and a 1 in 10 chance to do a bonus 35% attack damage on hit.
The issues with this come down to significant damage bonuses due to the fact that three attacks in a row could still ALL get the 10% chance to do 35% bonus damage. This i think will make this champion who they are though, the low chance means a probable high attack speed build that will maximise the passives effect.
Q: This champion focuses, dropping their attack speed by 30,25,20,15,10% for 2 attacks then maximising their attack speed and increasing AD by 15% for 2 more. This effect will expire after not attacking for 3 seconds. 6 second cooldown.
This ability combines a cost effect for a high early game reward allowing for an unexpected high burst. The 15% increase to attack damage also means it isn't useless when attack speed is maximised through itemisation.
W: This champion loads a exploding shot, causing enemy champions in the area of the attack target (including the target) to take 25% of his attack damage and applying on hit effects, including the passive.
This ability allows for an aoe effect shot that has a chance to deal the bonus passive effect along with any other on hit effects from items and buffs.
E: This champion knocks back any opponents within a 350 unit radius by 300 units and silences them for 0.5 seconds.
This ability is an effect designed for escaping and stopping any serious threats from channeling/using gap closing abilities instantly. This knockback effect is very small, however, it is justified by the fact it silences for a brief time.
Ultimate: This champion gets a rising movement speed buff for 3 seconds from 10-30% and raises attack damage by 20% The passive effect changes and this champion gets a 1 in 2 chance to deal 30% bonus damage on hit. This effect lasts for 7 seconds and the movement buff persists for 2 seconds after the effect has finished.
This is a typical trend for ADC's to have. A buff to damage and a bonus effect. This champion is designed to have a slower early game but have a very high late game damage much like vayne and kog'maw, however, it is obvious for this champion to take a higher attack speed than either of these if the build potential requires a choice to be made between damage increase and attack speed increase.
The maximum bonus damage on an auto attack becomes 90% of maximum attack damage when getting the passive, Q, W and the ultimate bonuses all at once.