***Aghanim/Octarine/Refresher should only be considered by extremely high skilled Invoker Veterans.***

Ask team mates nicely for 2 tangos at start.
Buy tome of knowledge ASAP as much as you can until max level.

Early game:
Last hit and harass with forge spirits or Alacrity during lane phase. You can also deny runes with forge spirits too!
Exort builds are not proficient in crowd controlling, so you might need your team to initiate. If you do not have enough time or mana to prepare your spells for battle, it is better to push down a tower. Chaos Meteor or Tornado (if wex/quas build) a creep wave, then use your Forge Spirit to pull incoming creep wave away, then use Alacrity. Doing this will give you a minimum of forty seconds to destroy the tower.

Mid Game,::
At level 5, 3 exort, 1 Quas, and 1 Wex is enough to do the following combo precisely: Tornado > Meteor > Cold Snap
Be aware of status resistance. After tornado, drop meteor asap, then cold snap when target hits the ground. You can finish the target with deafening blast or sun strike after 6 seconds.

Late Game:
It is almost always best to have Spirits summoned before battle, but be aware of their expiration. Furthermore, consider summoning Spirits during battle if you have a Force Staff. For example: Force Staff yourself next to Brewmaster, then use Spirits and Cold Snap right next to him. The stun lock will prevent Brewmaster from using Ultimate for several seconds. When ganking in most cases, start your first spell with cold snap or hex. After that, you can reassess the situation and do you see fit. Against big crowd controllers, I just cold snap the first target, alacrity the carry, and step back.

For hardcore Invoker comboes, check out my YouTube video guides:
Nuclear Strike
Magnetic Blast
Raging Fury
etc

https://www.youtube.com/watch?v=RuNiyHyPexQ&list=PLjzNcrzWWzgqaHbQ09PFeQHD0cc687HLO

For a complete Invoker Guide:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=185528211