Guard breaking a sure thing?

So, when you guard break with mag, sj lk hk, is it guarenteed? Or is it a guessing game? Say if they take the hit, the lk hits, then the hk hits, then ROM from there right? But if they block it, should the hk whiff? Or should it hit, then ad df lk (whiff) then start to ROM?

if they block the lk, and hk should hit, then dash pause, then lk,mk, rom

if they take the hit, the lk, hk will hit, and you need the reaction to then go into rom.

and if they pushblock, then you need know on which hit they did it. if they pushblock the lk, then do as if they had normal block, but pause a little before dashing down.

if they push block on hk, then dash hk, or hp so it whiffs, then either psylocke aaa, or just rom, i like to do psy, so i can start a reset.

hmm good shit, seems to work good that way. thanks a bunch