Alright, so i've been making maps for quite some time now on Starcraft, and I've (unfortunately) been using 'wait' triggers on my previous maps, and always noticed how strangely those maps had bugged, but now I've noticed to switch to Death Counters for delays in the triggers. But unlike how I had knowledge on using wait triggers, I have absolutely no knowledge on using Death Counters, could someone please help explain?

This should help: http://www.staredit.net/starcraft/Death_counters

The short version is, while using hyper triggers, you subtract 1 death count from a unit each trigger cycle.

There are 12 trigger cycles every 1 second, so you can use this to time things.

For example, if you want a 3 second timer, you set the death count for a unit to 36 (36 / 12 = 3).

You have a trigger that keeps subtracting 1 death count, and when the death count hits 0, you know 3 seconds have passed.

If you need additional information, the link that Sacrieur provided has a more comprehensive explanation partway down the page.