Spell thief stealing SLA from Summons

[Yogibear41]

If a spell thief steals/borrows a SLA from a summoned creature that would normally end when the summon ends, but uses it himself would the spell continue to persist?

For example a summoned lantern archon can cast continual flame, but the duration ends when the summon ends according to the summoning rules.

If a spell thief borrowed said ability and uses it instead, would it be permanent like a normally cast continual flame?

[Florian]

Nope. It doesn't matter that you cast the spell, it was borrowed from a summoned monster, so follows the regular rules.

[Darrin]

If a spell thief steals/borrows a SLA from a summoned creature that would normally end when the summon ends, but uses it himself would the spell continue to persist?

For example a summoned lantern archon can cast continual flame, but the duration ends when the summon ends according to the summoning rules.

If a spell thief borrowed said ability and uses it instead, would it be permanent like a normally cast continual flame?


Probably not, due to this text from Complete Adventurer:

"For all purposes (caster level, save DC, and so on), treat the spell-like ability as if it were being used by the original possessor of the ability."

And the PHB (p. 173) says:

"When the spell that summoned a creature ends and the creature disappears, all the spells it has cast expire."

It's not clear if the spell ends when the summoned creature disappears. It depends how you interpret "it has cast" or who you consider the caster to be, because although the spell effect inherits all the properties of the SLA from the lantern archon, the spellthief is still the *caster*.

It sounds like this is more of an "Ask the DM" kinda thing.