Killer cards

[RoundTower]

I remember reading this a long time ago. I think what it means is the number of cards your opponent has to kill your draw.

So for example if you have 89TQ on a 67Kr board, you have 13 outs. If you are up against a set your opponent has 7 outs to kill your draw, if you are up against top 2 he has only 4 outs. So you look for the intersection of the "13 outs" row with the "7 killer cards" or "4 killer cards" as appropriate.

Regardless, I think it is well explained in the book, just read it again.