sure i was at school so it was a quickie reply

in the book, Complete Scoundrel, theres something called Skill Tricks, which i can learn if i have the preq's for it..for example the one im mostly interested is Acrobatic Backstab..needing 12 ranks in tumble so i can buy it...says i can acquire this skill trick by investing into it with 2 points...1 for buying it i guess..and the other for rank 1? im not entirely sure, since it just says i should spend 2 skill points in it...Would it be a special type of tumble that i can do IF my DC succeeds ? or if i manage to get a decent roll... Would i also have to invest more skill points into it?
not sure if you have read it..maybe you can help out...