Help with explaining macro

[TarTime]

I'm using this macro

/use [@focus,exists,nodead][] Polymorph

and I understand what it all means apart from the [] bit before the spell name. Why is that there? / What does that do?

[Mordret]

There is great page called: Fitzcairn's Macro Explain-o-matic
you can find explanation of any macro.

But on topic [] matches any condition so it is always true. If it wasn't there your macro will only work on existing,not dead focus. Since you have [] if game won't match anything to first condition it will try to behave just like regular cast from spellbook.

[Brusalk]

It basically is a catchall. Think of it as an else in an if-else statement if you're familiar with those. Basically that'll cast poly on your focus if it exists and is not dead, and if the above was not true, it'll cast it on your target

[TarTime]

Thanks for the replies guys