That's easy enough to figure out. Just go to Lucy, pull up Yaulp V, click 'Stacking', and take a look at which spells have higher modifiers for the lines in question.
And that gives us...
Strength of Tunare (higher attack)
The above will probably overwrite Yaulp (not that this is likely, given Yaulp's very short duration), and will prevent Yaulp from being cast.
That's the only spell, other than Yaulp 6 and some chanter hastes that might cause a problem.
However, if we look at the other spells listed, we find...
Spiritual Vigor
This spell actually has a lower attack, but it includes the line
This means that if Yaulp is cast while this spell is up, Yaulp will bounce.
Ironically, the only reason that line is there is probably to block the spell Strength of Tunare.
And that gives us...
Strength of Tunare (higher attack)
The above will probably overwrite Yaulp (not that this is likely, given Yaulp's very short duration), and will prevent Yaulp from being cast.
That's the only spell, other than Yaulp 6 and some chanter hastes that might cause a problem.
However, if we look at the other spells listed, we find...
Spiritual Vigor
This spell actually has a lower attack, but it includes the line
Stacking: Block new spell if slot 1 is effect 'ATK' and < 115
Ironically, the only reason that line is there is probably to block the spell Strength of Tunare.



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