How to fix gangplank with one easy fix

How It is now

Parrrley

Cost: 50/55/60/65/70 Mana Range: 625

Gangplank takes aim and shoots an enemy unit with his pistol. If Parrrley deals a killing blow, he gains extra gold and half the Mana cost is refunded.

Gangplank shoots a target unit for 20/45/70/95/120 (+100% Attack Damage) physical damage. If Parrrley deals a killing blow, Gangplank gains 4/5/6/7/8 extra gold and half the Mana cost is refunded.Parrrley can crit and applies on hit effects as if a melee basic attack.

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Proposed Change

Gangplank takes aim and shoots an enemy unit with his pistol. If Parrrley deals a killing blow, he gains extra gold, **the cooldown is reduced by 50%, and the mana cost is fully refunded **