I'm going to be playing a chaotic wizard in an upcoming game. Slightly odd he specializes in Evard's Black Tentacles and Kaltim's Fiery Tentacles and I wanted an option to keep them more useful in late game so I intend to have him research the following spell. I made it chaotic and added the secondary effect to make it more unique and well personalized to the character (he's name is Laughing Tom because he laughs warmly in the middle of combat while dancing with himself). I figured I'd put it up, I'm fairly sure I could get my DM to agree to it, but I'm worried that it might be a little strong (or weak) and whether I should lower it's strength score or change the secondary effect. So:

(Tom's) Laughing Tentacles:
Conjuration (Creation) [Chaotic, Sonic]
Level: Sor/Wiz 6
Saving Throw: Will partial.

Suddenly the ground erupts in long, leathery tentacles. A multitude of colors, they laugh shrilly, a strange, almost musical, but undeniably horrible sound that chills you to the bone. The tentacles lash out wrapping around those within their area.

This spell functions as Evard's Black Tentacles except that the tentacles are huge, have 26 Str, and are 15-ft long. This means that their grapple check modifier is equal to your caster level +8 (size) +8 str and it deals 1d8+8 damage on a successful grapple check.
In addition any non-chaotic creature within the area is also shaken for as long as it remains in the area; lawful creatures remain shaken for 1d4 rounds after leaving the tentacles. This portion of the effect is sound-based and can be countered by a bard's countersong or other protections against sonic based effects (including deafness). A successful will save negates the shaken condition although leaves the normal effect unchanged.