On leftclick with any tool:
@set {_ench.%player%} to "18"
@wait 1 tick
@loop 10000 times:
@@add "1" to {_ench.%player%}
@@if player's tool is enchanted with knockback {_ench.%player%}:
@@@clear player's inventory
@if {_ench.%player%} is bigger than "10000":
@@set {_ench.%player%} to "18"