Steal Spell Effect

[Zaq]

So a spellthief can steal a spell effect that is active on the target. That seems simple enough... sorcerer casts Haste on himself, spellthief yoinks it and gains the effect. Easy.

But what exactly qualifies as an active spell effect? Assuming I have, say, True Seeing up, can I steal the Invisibility off of someone who slips on a Ring of Invisibility? If not, why not?

Assuming that the above case is valid, what about other magic items and their effects? Can I steal the save bonus from someone with a Cloak of Resistance on? It's just the spell Resistance, as listed in the item creation prereqs, only it reaches the target in an unconventional manner. If you think this is invalid, why do you feel that way?

The rules aren't as crystal clear as we'd like them to be, and I think that this is something of a gray area. Maybe even a grey area, if you prefer. I personally think it's reasonable for a spellthief to steal an item's effect from a character (note that you're not stealing it from the item, you're stealing it from the character), but other people might not feel that way. What do you think about this, and why?

[Katrascythe]

As I understand it you can't steal the spell effects granted by non-charged items. You can steal effects granted by wands and potions, but you can't steal the effect granted by a ring, amulet, etc.

I think the most basic explanation would be that it would be cheese-tastic if you had an item that granted an effect, then stole it. Stealing the permanent ability of an item to grant invisibility... a bit extreme but it serves for an example. A spell thief could steal the effect, but then the effect would be present again. So you got two effects of invisibility for the price of one.

[Baalthazaq]

Actually..

Possible interpretations of the rules:
You suppress the item for 1 minute per class level, so it doesn't duplicate.
You dispel the item when you take it, so 1d4 rounds of it being inactive, you keep the spell for 1 min per class level.
No, you can't, as you couldn't dispel the effect directly from the person.
No, you can't, as the ring is immune to sneak attack.
No, you can't, as the user counts as the caster, and he can't cast it on you.
No, you can't as it is duplicating a spell, it isn't simply the spell. (Resistance is not what a Cloak of resistance does, just like Disintegrate is not what universal solvent does. :P)

I think the final one gives you your real answer. It isn't performing a casting of the spell, it is creating a similar supernatural effect, so can never be stolen.

Consider: Universal Solvent. Spell required is disintegrate. You can now buy disintegrates for 50gp a pop.

[Dr_Horrible]

Actually everyone, the rules are:

1) You can't steal the effect of a Cloak, because it's not the spell resistance, it's an item effect.

2) You can steal the invisibility of someone who has activated a ring of invisibility. Look up the actual item. It doesn't grant invis to someone wearing it. It can cast it on them as a standard action. So once they activate the ring, it's exactly like some caster cast the spell on them. And you can therefore steal it.

[herrhauptmann]

So the steal effect lets you steal a spell which has already been cast?

Say you walk into a room, there's the BBEG and his blackguard already buffed up. Can you start stealing buffs from them, even though they were cast before you got there?
I had always thought you could only steal when you see the spell being cast, or the item activated.

[Keld Denar]

Nope, if they have an ongoing spell effect on them, you can steal it. And like was said above, the effects of continuous items can't be stolen. You can't steal the resistance bonus of a cloak of resistance, or the str bonus of a belt of giant str. I think there is verbage in the class discription that states that you can determine what spell effects the target is affected by when you hit them and attempt to steal spell effects.