UPDATED: True Strike + Impr. Trip [Confused about Tripping]

[Hypersmurf]

No, you don't get the benefits of the True Strike spell more than once. The text of the Improved Trip feat refers to your normal combat modifiers only, basically stating that you get a bonus attack at the same BAB and other normal adjustments that the initial trip attack used. So, if it was your third attack in a full-attack sequence, it would be made at your normal BAB -10.

The feat itself is not supernatural or magical in any way and does not affect the duration of spells.

Same goes for Cleave. "at the same bonus" refers to the BAB of your iterative attack; any conditional modifiers are applied to the Cleave attack as usual.

So if you drop a evil hobgoblin from your horse with your goblinbane sword while smiting evil, then Cleave into his neutral Dire Wolf buddy, you don't get:
1. the extra +2 for Bane (he's not a goblin);
2. the extra +1 for attacking from higher ground (he's Large);
3. the extra +Cha for the Smite (he's not evil).

Likewise, if you hit the hobgoblin with True Strike, the spell is discharged... so the +20 can't apply to the dire wolf - there's nothing to provide the bonus.

-Hyp.

 

[Egres]

What if you then MAKE the strength check, and the guy is tripped, and you have imp. trip, triggering the free attack?

You "gain a melee attack against that opponent as if you hadn’t used your
attack for the trip attempt."

Does this mean you get the True Strike +20 once again, plus 4 for the opponent being prone?

From the 3.5 FAQ:

Suppose a character with the Improved Trip feat uses
the Bluff skill to successfully feint in combat and uses his
next melee attack to trip the duped opponent. It seems clear
that the character ignores that opponent’s Dexterity bonus
to Armor Class for the touch attack to initiate the trip.
Assuming that the trip attempt is successful, Improved Trip
provides an additional attack as if the character hadn’t
used her attack for the trip attempt. Does this mean that
the character continues to ignore the tripped opponent’s
Dexterity bonus to Armor Class for the additional attack
granted by Improved Trip feat? How do other “next attack
only” effects (like the true strike spell) work with the
Improved Trip feat?

In each case, the initial attack in trip attempt is the “next
attack,” not the extra attack that you get from the Improved
Trip feat. That is, if you’ve made a successful feint, your foe is
denied any Dexterity bonus to Armor Class when you make the
initial melee touch attack to start your trip attempt, but not
when you attack him after a successful trip. Likewise, if you
use the true strike spell, the +20 attack bonus applies to the
touch attack, not to the free attack.
The Improved Trip feat description says that you get an
extra attack after a successful trip attempt “as though you
hadn’t used your attack for the trip attempt.” That, however, is
just a shorthand way of explaining what part of your normal
attack routine you use for the extra attack; it’s not meant to
imply that you enter some kind of strange time warp when you
make trip attacks.

 

[darkelfo]

I think there's a Quarterstaff of Sweeping in Magic of Faerun that grants the wielder the Improved Trip feat. This may just be a special weapon, or it might imply that a Quarterstaff can be used to trip.

"Sweeping" is a special weapon ability found in Magic of Faerun. I believe its a +1 bonus. It grants +4 on the opposed strength check in a trip attack, if memory serves me correctly.

Sweeping Weapon, Plus Imp. Trip, plus high Str is a pretty neat combo. Especially with Boots of Steadiness which for overkill makes you immune to trip attacks.