Tentacular Guidance: The spell is a bit better than most level two spells, but not enough to warrant a three, I think. True strike gives a +20 to attack, and a similar spell by Monte give a +20 to attack, but only if you would otherwise miss (and then the spell is discharged), and is level two, though it requires a feat to use. That's about the limit of the yardstick for automatically succeeding at a check with a spell, as far as I know, however. An almost-automatic success at a skill check is a bit better than a single attack roll, so I'd guess the level is about right.