jaelis
Oh this is where the title goes?
Well, you can't ordinarily set a spear vs a charge, but maybe you've anyway houseruled that?Then you just ready an action to hit them as they come straight down, and I would grant a bonus if it’s a weapon you can set against a charge like a spear.
Certainly readying an action works, but not so well if you normally get multiple attacks. In any case, regardless of how effective it is, I guess most people would find the jumping thing insufferably cheesy.