How does Eldritch Conduit for Rogues Work?

Question

Use Magic Device (page 109, Core Rule Book) says

Use a Scroll: Normally, to cast a spell from a scroll, you must have the scroll’s spell on your class spell list. Use Magic Device allows you to use a scroll as if you had a particular spell on your class spell list. The DC is equal to 20 + the caster level of the spell you are trying to cast from the scroll. In addition, casting a spell from a scroll requires a minimum score (10 + spell level) in the appropriate ability. If you don’t have a sufficient score in that ability, you must emulate the ability score with a separate Use Magic Device check.

So, my 3rd level rogue has a 10 INT, 8 WIS, 14 CHA, a +12 UMD, Eldritch Conduit and just got a Scroll of Magic Vestments.

He also has a Scroll of Shield he'd been saving.

Eldritch Conduit (page 7, Magic Tactics Toolbox) says

Eldritch Conduit (Su): Survival in the Mana Wastes between the nations of Nex and Geb can depend heavily on locating sufficient magical equipment, which sometimes involves stealing power from a wand or scroll to power a more necessary one. As a full-round action, a rogue with this talent can use two potions, two wands, or two scrolls. Each item is expended or loses a charge as if used normally. The rogue chooses to gain the magical effect of one, but calculates its effects using the caster level of the other. The rogue must still succeed at a Use Magic Device check to operate scrolls or wands unless some other ability allows him to do so, but makes only one skill check to operate both items.

My question is Would I need to emulate an 11 INT, 11 WIS, 13 WIS, both an 11 INT and 13 WIS, or none since you only make one check for both? I'm assuming the CL DC would be 21 based off the Shield spell?

Answer 1

I read Eldritch Conduit a little bit different. I see it as having two key parts:

The rogue must still succeed at a Use Magic Device check to operate scrolls or wands...

...makes only one skill check to operate both items.

By my reading, you must activate both items using your one check. To me, this says that you must meet the higher DC between the two items. Otherwise you'd fail to activate one of the two.

In your example

You would have to beat a DC 28 on your UMD

• By rolling a 28, you Emulate 13 Wisdom for Magic Vestment

You also:

• Beat Use Scroll of Shield's DC 26 (to emulate 11 Int)
• Beat DC 23 (Use Scroll of Magic Vestment)
• Beat DC 21 (Use Scroll of Shield)

If you were to wear a Headband of Inspired Wisdom +6, your DC would become 26. If you were to wear the Headband and increase your Int to 11 at level 4, your DC would drop to 23.

Another Example

To adopt another answer's example, using Scroll of Cone of Cold (5th/CL 8) at CL 15 via Scroll of Summon Monster XIII(8th):

• Your DC would be 35 (to activate a CL 15 scroll).

Because this also succeeds at the:

• Emulate Intelligence DC 33 for Summon Monster XIII
• Emulate Intelligence DC 30 for the Cone of Cold
• Use Scroll DC 28 on Cone of Cold.

Altering your ability scores would not alter this DC.

Answer 2

The special ability eldritch conduit as originally printed allows a creature to take a full round action activate one magic item, expend a second item (or expend a charge from a second item), and use the second item's caster level for the first item. Both items, apparently, must be of the same kind.

The text says, "The rogue must still succeed at a Use Magic Device check to operate scrolls or wands unless some other ability allows him to do so, but makes only one skill check to operate both items," so I assume the Use Magic Device skill check is for the item that's actually activated rather than the item that's expended or from which a charge is being drawn.

For example, a rogue possessing the talent has an arcane scroll of cone of cold (5th-level spell at caster level 9) and a divine scroll of summon monster VIII (8th-level spell at caster level 15). That rogue can take a full round action to activate the scroll of cone of cold and expend both scrolls so as to up the cone of cold spell's caster level to 15. If that rogue's Int is less than 15, the rogue must make a Use Magic Device skill check (DC 30) to emulate that ability score, and—either way—must also make a Use Magic Device skill check (DC 29) to activate the caster level 9 scroll of cone of cold.

For example, a rogue possessing the talent has an arcane an arcane scroll of shield (1st-level spell at caster level 1) and a the divine scroll of magic vestment (3rd-level spell at caster level 5). That rogue can take a full round action to activate the scroll of shield and expend both scrolls so as to up the shield spell's caster level to 5. If that rogue's Int is less than 11, the rogue must make a Use Magic Device skill check (DC 26) to emulate that ability score, and—either way—must also make a Use Magic Device skill check (DC 21) to activate the caster level 1 scroll of shield.

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Note: The rogue talent eldritch conduit on the d20PFSRD is rewritten from its original appearance in the Magic Tactics Toolbox to avoid violating the OGL, and, in the process, it seems it was changed overmuch. The original version makes much more sense.

Answer 3

This question seems very similar, and though the quoted SRD text doesn't mention ability scores it does mention the other necessary conditions typical for a character to use a magical device without the use magic device skill. I believe it is safe to assume that the PFSRD would have explicitly mentioned the need to make multiple rolls to activate a scroll if you had to make a separate check to emulate ability scores. Similarly, the above is effectively a single skill check to activate the magic item and discharge the other, no additional emulation required (unless the effect is ongoing - see original SRD content).