Use magic device for wondrous items?

[momoya]

A character in my group wants to use a crystal ball for scrying. They're a level 4 wizard, so they have scrying on their spell list, but not yet available.

If the item were a scroll, I think it would apply that only if "her caster level is at least equal to the spell’s caster level" she can use it without making an UMD check. But what's the "spell's caster level" in this case? The page of the orb says it's CL10, so I assume only a level 10 wiz would be able to use the scroll without a further check.

Applying these rules to the orb directly (since its practically equivalent to an unlimited use scroll, right?), she would have to make a caster level check with a DC of the orb's CL (10) +1. She can add her 4 wizard level to the d20 roll to surpass, so the check has a >50% chance to succeed and can be retried on fail with a DC 5 wisdom check.

Did I get all of that right?
It seems like UMD isn't required at all to be rolled here, even though the case is exactly this: Using a magic device that one is unfamiliar with.
But after all, on the entry to UMD it says: "Use Magic Device lets you use a magic item as if you had the spell ability or class features of another class" which, doesn't apply since the wizard does have scrying...?

Then again, finding a crystal ball and knowing that there must be something special to it, one would assume that it's most likely an orb of scrying. But that's only a good guess, while properly identifiying the properties of a magic item is a DC15 + items CL spellcraft check. Would she need to pass that check as well, before she could make an attempt at using the item?

If not, there's also the option to "use device blindly", which should apply when the device would require something like a password to use, which might as well be the case here.

I'm sorry if my wording here is a bit confusing, but with all those rules that seem like they might apply here, I can't really figure out which ones to actually use...

[Azothath]

in a practical (in Game) way - a magic crystal ball is way too expensive for 4th level characters. IF you manage to get your hands on one have fun. The spell Scrying is on a Wizard's spell list (see rules link below). A few creative GMs use Int/Wis/Cha score or bonuses. A Pathfinder's Coin might be practical. Remember too that an Arcane Mark is easy to locate, so you might try that with some skullduggery...

Scroll use - again, in a practical way a scroll of Scrying:D4 is not an efficient use of capitol(gold pieces) for a 4th level party. Likely the scroll won't go off or it'll result in a mishap. Scrying also requires knowledge of the target to work well AND it's easy to detect (alerting the target). I'd suggest; Discern Next of Kin, Detect Thoughts, Locate Object, Psychic Reading, Blood Biography, Seek Thoughts, or Locate Creature, then Clairvoyance or Scrying.

The >rules for scroll use< are in the CRB. Everything needed is IN the scroll (consider the scroll the focus). Check the user's spell list (Scrying is on a Sor/Wiz list so they can avoid UMD). Next are Primary Ability Score bonus, then Caster Level. The d20 role is in RAW.
It is easier for casters to use Item Activation than Use Magic Device(UMD). UMD is for rogues and character's not trained in The Art(magic). Some spells are not on a caster's spell list and then it can get tricky. There are several feats that provide access usually increasing the spell's spell level by one.

[Tom Sampson]

Use Magic Device is not used at all for this. Anyone can use a Crystal Ball. It doesn't ask you to be a Wizard or to know the Scrying spell. The Crystal Ball handles the scrying on its own. You just have to use it, and since the item doesn't present any requirements or restrictions for its use, anyone can do that.

Use Magic Device really isn't a skill you need for activating an unfamiliar magic item. For an unfamiliar item, just identifying it with Knowledge (arcana) or a Spellcraft check while using Detect Magic will help you figure out how to use it and that's all you need, really. (If it requires you to figure out an unfamiliar command word, it's a DC30 Knowledge (arcana) check, but identifying it with Detect Magic and a Spellcraft check will tell you the command word anyway.)

Just to be clear, magic items are typically usable without any UMD check at all. So if a magic item were to state that you need to be a Wizard to use it and you happen to be a Wizard, then you don't need UMD. You already qualify to use it, so you can just use it. The UMD skill exists for circumstances like "the party thief/rogue got his hands on a magic scroll" or a fancy magic dagger that shouldn't work for members of his class/race/alignment/etc, so he rolls UMD and he gets to use it anyway. If the Wizard wants to use a scroll with a Wizard spell, he won't need UMD. He can just go ahead and use it. If the Rogue wants to use a scroll with a Wizard spell, he does need to roll UMD.

[Mysterious Stranger]

Spell completion items like scrolls require you to be able to actually cast the spell. Spell trigger items like wands and staves require the spell to be on your spell list, but you don’t need to actually be able to cast them. There are also other magic items that have additional requirements like belonging to a specific race or having a specific class feature. A crystal ball is not a spell completion or spell trigger item, nor does it have any additional requirements to use.

Most magic items require you to identify them before you can use them. Crystal ball does not specifically state it requires this but seems like it should. Every GM I know would require this, myself included. The only time you might need to use UMD on a crystal ball is if you had not had not successfully identified it. The Activate Blindly aspect of UMD is used to activate magic items that you don’t know how to activate.

[Dragonchess Player]

The rules on Using Magic Items differentiate magic items into four categories: Spell Completion, Spell Trigger, Command Word, and Use Activated.

Scrolls are spell completion items, a wand and staff are spell trigger items; most other magic items are either activated by a command word or by a specific use condition. In general, unless the item description states a specific action to activate it (firing a magic arrow; "as a move action, cover his face and drop to a huddling crouch" for a cowardly crouching cloak; etc.), you should consider an item with a non-constant effect as requiring a command word.

For discovering command words:

Quote:

The Knowledge (Arcana) and Knowledge (History) skills might be useful in helping to identify command words or deciphering clues regarding them. A successful check against DC 30 is needed to come up with the word itself. If that check is failed, succeeding on a second check (DC 25) might provide some insight into a clue. The spells detect magic, identify, and analyze dweomer all reveal command words if the properties of the item are successfully identified.