Line 20836 is
Deaths("Player 2", "Unclean One (Defiler)", At least, 1);

No idea why this is happening, there is a ":" there.

That wouldn't happen to be your very last line would it?

No, there's ~72000 lines.

The error is on line 20835, zero based, which is what the bottom left corner of the screen reads.

That's
Conditions:

Doesn't help much, I suppose, but try deleting that trigger, then remaking in classic.

Found the problem. In Notepad++ it has some non-text formatting properties. When I copied from Notepad++ to Notepad (yeah, the old crappy Microsoft thing) all the formatting disappears. Wrote a quick C++ program to format it and compiles fine now.