Imma toss a +1 to that. It's convolutedness leads to confusion, but it's so open ended that the users can find themselves making the OT theirs; imprinting themselves on how they work the OT's abilities (or vice versa).
I would also say the manual, plus Merlin's doc, and MAYBE the Octatrack Know-.How (which are, in playing the Elektron mo, vague enough to not be pedantic...just the facts, ma'am).
The others (afaik) are good for ideas you may have missed (definitely inevitably)
But above all, patience. It's worth it. I've had mine for over 6 months and after using it constantly I know I'm still using only 7% of it. But oh what a sweet 7% it is.