We don't get the attacks from the ancient ones. It is impossible to defeat them.
For example "Glaaki", his attack text is "Raise the terror level by 1. If it is 10 or higher, all investigators are devoured". His doom track is 12. 12 - 10 = 2! ;-)
But it means that it is impossible to go father back then doom track 2? Always doomtrack no 1 and 2 stays with a doom token and all investigators are devoured.
Monster "Yig" same story. After each round the modifier decrease by 1. So after 7 turn no investigator has any sanity or stamina left, so you never come beyond doom track 2.
What do we do wrong?

. Also, if we assume the # of dice is the same each round, getting 6 hits on turn 2, then getting 13 on turn 3 merely balances the odds.