-5 to hit for a minimally effective attack? No thanks. Why wouldn't you just murder the **** out of it with a regular attack? If they wanted to make the knockdown occur without a negative to attack, but a minus to damage or something. Like others on other forums have said, with bounded accuracy, these attacks just aren't worth it.
Should mention flying, hovering, and swimming creatures. As written, there's no penalty for 0-legged creatures, so any successful melee attack automatically bounce-passes a Beholder. Which... actually, that kinda makes sense.Knockdown (–5 or –10)
(You bowl your enemy over, knocking him down.)
Effect: The target falls prone.
Penalty: This action has a –5 penalty if the target has two legs, has a –10 penalty if the target has three or four legs, and cannot be attempted if the target has more than four legs. You can attempt this action only against a creature of your size or smaller.