So I am looking at the Quarterstaff of Vaulting...
This +1/+1 darkwood quarterstaff grants superior balance and acrobatic skill. It glows with a faint green-yellow radiance when in use and can extend to nearly double its length, though only when being used to perform acrobatic feats. The wielder gains a +5 competence bonus on Acrobatics checks and can move at full speed without penalty when using Acrobatics to move on narrow surfaces or uneven ground. When making a high jump while wielding the quarterstaff of vaulting, the Acrobatics DC is equal to 3 times the height to be reached instead of 4.
In addition, with a successful DC 25 Acrobatics check, the wielder can use the staff to vault over an opponent's head in place of taking a 5-foot step. She can only use this ability on creatures no more than one size category larger than her, and must end her movement in the nearest adjacent square on the opposite side of the creature. If this square is unavailable, she cannot use this ability. This movement does not provoke attacks of opportunity.
The bolded part is the important part here. I am hoping there is a way I can trick the Quarterstaff into thinking my PC is larger then it really is (I would love to just vault over a Colossal creature!). Any suggestions?
HUH....would that really work?
UMD to emulate something allows you to use the item, it does not change the mechanics of how it works. If that was the case you could "trick" a ring of enlarge person into treating you like a huge or gigantic humanoid (if any exist) and making you one size larger than that. But obviously that's not how it works.
The only way to jump over larger creatures with that pole is to be larger yourself.
I can see where you might be reading that the magic item is refusing to help you jump the giant because you're not an ogre. I don't think that's the case. I think the magic item is helping you vault, and the writer found or made up some vaulting-related text as one of those clarifications that muddy things.
Like text on 'X of the Titans' needing the user to be large-sized, it's not about a willful resisting magic item to be fooled, it's about physics.
Should have said, "...user can vault over enemies up to one size larger than themselves."
So conclusion is that UMD would not work for this case? Is there anything else that might work? A spell or something that allows you to "be treated as one size larger" or something of that nature?
I agree with the rest in that the RAI means you need to adjust your own size.
Enlarge Person is one way. Some spells transform you to larger-sized creatures, but that means you need to be careful with the text of the spell, as it might not say your items grow with you.
If you can figure out a way to become a cloud giant or storm giant then you would be huge size category. That's the largest size any humanoids come in I think, and you need to have hands to use the weapon which generally means humanoid. That would allow you to vault over gigantic creatures.
All said and done though, you're probably better stocking up on potions of fly at only 750 gp each.
Oh well. It was worth a shot. I still like the item as is and I was just trying to get a bit more mileage out of it.
Rune Giants are Gargantuan Humanoids with the (Giant) Subtype
if you can trick the item into thinking you are a Rune Giant, you can jump Gargantuan creatures
but there aren't any collossal humanoids
unless your DM lets you fool the item into thinking you are a behemoth. which are 3rd party monsters, that happen to be collossal magical beasts with humanoid anatomy.
Rune Giants are Gargantuan Humanoids with the (Giant) Subtype
if you can trick the item into thinking you are a Rune Giant, you can jump Gargantuan creatures
but there aren't any collossal humanoids
unless your DM lets you fool the item into thinking you are a behemoth. which are 3rd party monsters, that happen to be collossal magical beasts with humanoid anatomy.
But according to everyone's opinions so far that would not work.... Even if I trick the item into thinking I am a Rune Giant or anything else for that matter, would not allow me to jump creatures that are =>2 larger then my ACTUAL size
For what it's worth, if you have a high enough acrobatics skill you could just jump over creatures. Of ourse, vertical jumps have a high DC, and the only way you're really going to manage it is to be a monk of at least 5th level (for the High Jump ability) and event then you'd probably need to convince you're GM to let you have an item that gave you +30 to acrobatics. The DC to jump over a 10ft tall creature would be DC 40.