Yeah, I have a whole whack of different books for assassin spells, no worries there.

Also, of the classes that were listed to also use Death Attack, I found that none of them really catered to the character (At least from the books that I have.) The levels would just be better spent on rogue. I do plan on maxing Assassin to 10 to max out the DC as much as possible, and focus on int and dex at character creation.