For example on Rogue using Shift specialized.
Lasting presence - You leave behind a shadow at the place you shifted from. Shadow created after shifting.
Ok. but what does the shadow Even do??
Also leveling a skill i think you should be able to see what/how much will increase when adding a point in that mastery or skill. For example Deep Strikes - Damage: +8% Next level +12% or something like that. to see if its worth adding the point into it.