Originally Posted by crummywizard
Aghanim should be Invoker's father or something lol
Now that would be an interesting addition to the Dota story.
Aghanim is Rubick's father.
Anyways, I suggest to fix mana problems first, get Aghs second. You won't need more than 3 spells most of the time anyways (due to most of your spells being not leveled up).
Also I don't think Invoker has something to Refresh effectively.
All in all, I'd reccomend this guide:
Not a tl;dr guide you probably want, but one of the best there. Or just browse Guides section for more.