Excellent. Back to work:
I like it. The mechanic's quite sound, and solves the 1st-level-orc-shoving-Elric-around problem.
But it doesn't yet address the hink I have with the trip mechanic -- advantage to the nimble guy. Not a huge advantage, but some advantage. Something for the nimble guy to choose as a character technique, like Weapon Finesse. The strong guys have got Bull's Rush, and feats like Knockdown, which use the existing Trip mechanic, but seem to tacitly admit that there's a different "style" of making somebody fall down here.
At least, a trip's got to be something worth risking. Odds are, you lose your trip attempt, you're going down. And nimble guys should be harder to trip (which, admittedly, is taken into account in the STR or DEX factor in the trip attack defense). And still, inexplicably, Improved Trip seems to give you no greater advantage in actually making your opponent fall down or helping you stay up.
And although I understand the "no size difference" ruling, I respectfully disagree. Dragon SNATCH abilities are size dependent, etc., it's a logical mechanic. But, as you said, go for it.
How about this:
You may make a Trip attack as a melee attack.
You may use a weapon in your qualifying melee attack and trip attempt that is either made for tripping (see weapon descriptions) or is at least ONE SIZE LARGER than your opponent. i.e. it's reasonable to think one could tangle up the legs of a Medium sized opponent with a large-sized quarterstaff. A large Ogre, on the other hand, would not be so vulnerable. Otherwise, it's a simple touch attack drawing no AoO.
DM's OPTION: you may not make a trip attack on an opponent more than one/two sizes larger than you.
1.) Make a melee touch attack. If you succeed, move to step 2.
2.) Make opposed TRIP CHECKS. A trip check is identical to a grabble check, except a character's DEX is used instead of his strength.
TRIP CHECK: BAB + DEX + SIZE MODS + (MISC WEAPON MODS)
If an opponent stands on more than two legs, it receives +4 to it's trip check. If it is unusually stable, it receives another +2.
NOTE: I see the reasonable objections coming. "Then a high dex thief could shove a fighter around." But wait, the BAB for high Dex characters tends to be just lower, tilting that part of the equation back towards the fighter. And if you're a high DEX fighter, then, well, this would naturally be part of your repetoire as opposed to Power Attack, Bull Rushing, Knockdown and the like.
3.) If you succeed in your Trip attempt, your opponent is prone. If you fail, your opponent may now make a free trip check against you, without needing to make the melee touch attack. (You have theoretically "opened yourself up" to this attack by your attempt.)
Tripping weapons function exactly as they do in their descriptions, including the ability to drop them to avoid the countertrip.
This mechanic works best with the following feats:
IMPROVED TRIP: (prereqs same) When you make a trip attack, your opponent may not attempt to countertrip you if your attack fails. this brings the feat more into line with IMPROVED DISARM and SUNDER
FOLLOW-THROUGH: (prereq, Expertise, improved Trip) When you make a successful trip attack, you may then make a melee attack on the tripped opponent at the same base attack that you made the trip attack. (essentially, what's now IMPROVED TRIP in the PHB is this feat.
SLAPDOWN: (prereq, Str. 13, and ???): During trip checks, you not only use your STR value instead of your DEX, you force your opponent to do so also.
(the logic here is -- hey, a fighter wants to spend a feat so they can trip folk instead of grappling them, cutting them into small pieces, shoving them about, etc, let 'em. Still thinking about the prereqs...)
An alternative to this could be, leave the Trip mechanism as is, or use the BAB version of Corwin's (makes sense) but make the feats:
IMPROVED TRIP: When you make a trip attempt and fail, your opponent may not make a countertrip attempt.
UNDERFOOT: (prereq Improved Trip) When you make a trip attempt, you not only use your DEX mod instead of your streength mod, you force your opponent to do so as well.
How's your tweak game-playing, Corwin?
