[SCRIPT] Make an item appear after smashing plates?

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Now I just need to break it down and learn what certain things do. Like the whole local variable thing confuses me a lot :/

Well a local variable is just that - a variable. It has a name and a value - the name always stays the same, but the value can change. So basically it let's the script "remember" a value for later use.

One of it's most basic uses is counting things. So in this case, you create a variable that shall count the number of broken plates:
VarInt means that the variable is an integer, or a whole number. (like 1,2,5...), BrokenPlates is the name and 0 is the start value.

The if statement later on then simply uses AddLocalVarInt to add 1 to the variable every time a plate is broken. It also says that if the number of broken plates is 5 (which means, the variable BrokenPlates has a value of 5), the key shall appear. And that's pretty much the whole magic behind this