Okey then there is one thing that seems like not make sense at all-why all those one hit mobs/animals on the list? I think it would be better if only count mobs that are harder to kill/
Also for 5%extra dmg no way anyone would go after 5000 champ bosses bcs its crazy amount to kill. 
Thats all from me. 
This system got potential like make those kills in tier
Each time player reach one of those could get unique rewards that would bring more joy from doing it. 
Like champs max required kills at 500 and each 100 pay out with 1use of some old school dyes like 1920 for mephistis cuz its crazy green and meph as spider poison things. Otherwise i dont think there would be any reason to bother for those kills.