It's already way weaker than Shadow Simulacrum, the HD limit makes it useless.
The duration is 6 seconds per caster level, you're not going to a level 15 area then running to where you want to be.
There are way too many broken or useless spells; we need more worthwhile choices.
You raised the damage cap on many spells like Magic Missle so they could be used at later levels, this would continue that trend.