It'll have +30 attack damage, +40% attack speed, do almost double the damage per tick of the Blackfire, scale with attackspeed, have inf charges and be 200g cheaper!
I wonder what riot will call this clearly overpowered item made from a Pickaxe and Recurve Bow.........
If you still can't figure out I am being sarcastic, here are some numbers.
Blackfire damage per second vs 2K hp = 33.3
Kitae Per hit vs 2K hp = 50
Wits End per hit vs anything = 42
Blackfire is fine. You are just not used to casters having damage options. If you want something with the same "stats" as blackfire, Ghostblade is still there, same place it has always been