Spawn gems(items) with speed, remove item from player inventory when hitting mob

I have two problems.
I want this item to make a bunch of items "explode" out when i hit mobs with them, have them spawn at X Y Z, with random X Y Z speed. I cant have them spawn at random location, since some of them will get stuck in blocks. Kind of like when you break a Compact Drawer, or YABBA barrel when they have lots of items in them.

When i hit a mob with that item, the [Remove 1 (item) from provided (entity)player's inventory] does nothing. Item count does not go down. Is it targetting the attacked entity?