I Maximize My Item-dropping Rate

After mistakenly contributing all of his attribute points to the drop rate, Xiao Shi found that every time he killed, he would get an item.
Slapping a mosquito to death, drop a pill.
Killing an evil spirit, drop a secret book.
Slashing a martial artist to death, drop the opponent’s cultivation tips.
….
When killing, Xiao Shi was shocked… “How did I become invincible?”