If the bomb counter is defined the same way the runestones counter was (before S8 made it invisible), it's at least a 2-byte variable.
If it's defined as a signed integer, the counter can reach 32,767 before there is a problem. If it's an unsigned integer, the counter can reach a maximum of 65,535.
If it's a 1-byte unsigned integer, the maximum will be 255.
All of this assumes S8 didn't put anything in the code to keep the number lower than the maximum possible for the variable.