Starcraft 2 Galaxy Editor Triggers

[KyllaSnyper]

I have got 98% of my map in galaxy editor complete but I am missing one key element. I want my maruaders to be replaced with marines after fifty kills

 

[ShadowFlare]

Use. Variables.

have a separate trigger for whenever a unit dies set x = x+1
when x = 0 spawn XX1 Unit
when x = 100 spawn XX2 Unit
etc...