This build focuses on so that by lvl 10 you have 2 forged spirits, and have the potential to gank and deal massive damage with the Cold Snap Forged Spirit Combo. Near the Mid to Late game, it well then revolve around massive damage with the Euls Combo (Euls, Sunstrike, Meteor, Defening Blast) to help with pick offs, and then prepare you for team fights.
I decided to put the Manta Style and Necro in there because these two items work very well on Invoker. Cold Snap + Forged Spirits + Necro Minions or Manta Style + Auto Attacks it is a crazy amount of mini stuns and practically guarantees an easy kill. If your team is lacking push Invoker can turn into a great pusher, so these items can be a sure pick for him.
There will be times when your abilities are not cutting it anymore whether you may be falling off because the team is becoming to tanky or they get BKB's. What ever the fact may be, adding one right click can make a huge difference.
Desolator and your forged spirts will shred armor allowing for hard to kill hero's to be easier to take down.
Daedalus allows you to have a good amount of extra damage plus a crit. So a possible way this is good, if you put alacrity on yourself you gain extra damage plus attack speed, then you can top it off with forged spirits and cold snap. You will be dealing ridiculous damage just due to the fact of the armor shred the crit and boosted attack speed plus the extra damage from Daedalus and alacrity.
Mjolliner because it gives a major attack speed boost and gives a boost in damage as well. The static charge also created by your auto-attacks are also very useful!
This build focuses on damage and the easy way to kill enemy hero's! When playing Invoker mid or offlane, use your forged spirits to harass the enemy and when a golden moment appears cold snap, your forged spirits will be hitting them, then you auto attack as well! if the enemy has not died by then, while they escape do Exort x3 which is sunstrike, and hit them while run!
Never be afraid to play aggressive and do what you can to win your lane, unless the enemy has you completely out matched. If they have a lane with perma stuns, or with lots of escape, or just more damage than you can't handle. In that case, farm safely get your levels, last hit with forged spirits so you're not out there yourself and progress through the game that way.
You don't need to follow the build exactly! Invoker is a very flexible hero, and all the items listed work well on him. You do not always have to buy a euls or an orchid. This build is just stating possible items, and giving you a better understand on what works well with Invoker and how I like to play him.
Me personally, I like an Invoker that can deal massive damage in team fights, and get easy pick offs, hence the Scepter, the euls, and the Orchid. I also love mobility and Boots of travel allow invoker to move ridiculously fast making me even harder to kill.
So I hope you enjoyed and found the guide useful! and GLHF in your future games!