You could use group or global variable
eg with global variable:
set global variable "Timing" to 1.5
set global variable "MagnitudeSine" to 40
every "Timing" sec -> spawn enemy
score >= 100 and trigger once while true (or whatever you want) --> substract "timing" 0.5 and add "MagnitudeSine" 40
on enemy (or another object with sine behavior) created --> set enemy magnitude to "MagnitudeSine"