In my opinion, Rengar loses out because his Q is on a really high cooldown (comparatively - Parrrley, Taste Their Fear, Spear Shot, etc, are all much lower) and his ability to initiate fights requires his ultimate or a brush. Kha'Zix not only has lower cooldowns, but he has a jump-skill rather than a jump-passive. He can do it whenever. He also has an AOE ranged slow, whereas Rengar's is single target. Rengar literally has worse versions of each of Kha'Zix's skills.
In my opinion:
- Savagery: Rengar gains increased attack speed for 3 seconds and his next 3 attacks deal bonus damage. The bonus damage decreases by 33% with each hit and refreshes the duration of the attack speed steroid. Physical Damage: 30-20-10 / 60-40-20 / 90-60-30 / 120-80-40 / 150-100-50 (+100% AD). Activating still resets the attack timer
- Empowered Savagery: Rengar's next 3 attacks deal additional damage equal to 50% of his attack damage, and the bonus attack speed is doubled. (Possibly also have it so that the bsae damage doesn't decrease with each hit).
- Battle Roar now grants the bonus armor and magic resistance to nearby allies. Empowered Battle Roar could also heal allies.
- Empowered Bola Strike's visual "net" will not slow any enemies who walk over it for 2 seconds.