The starting items I've chosen are for rushing phase boots. This is my personal preference and is only viable on quas starters like this build because it gives you major lane sustain so you're not forced to buy starting regen to much. but if you're not as comfortable with invoker or like to even out your early points a little more you may want to switch the for 3 gg branches, a salve, a tango and a part of your bracer.
The laning items I suggest are made to get you to and from lanes as fast as possible so as to make ganking as easy as possible when the time is right. Make sure you have your support maintain ward placement as well because it is very vital for the team in general but for ganking invoker even more so. I recommend getting your boots and finishing them into phase followed by your bottle. then you can choose to finish your wand and bracer if your farm is good enough or buying your force staff and perhaps a tp scroll to get in there and gank.
As normal with a Quas-Wex build you generally want to build race car style and pick up a drum for team fights and an ulti stick. All pretty basic stuff and keep up tp scrolls so you don't get caught off guard with a back door attempt or because you pushed up to far.
These items can be useful or needed depending on your team so keep them in mind. If your supports are being ****s in chat and have started buying cary items because "cary kotl best hero" then you may wanna be the good guy and pick a mek up for all of your teammates that do still have hope for the game. A veil is overall good for invoker but most times it can be much better to buy one of the final items I've set out to choose from, the times you do want to buy it is when it will benefit at least two other heroes in your team to have it. Make sure to communicate with them that you have it though so they can coordinate a good team play on it. A nec can sometimes be a good choice as if you have failed your lane and do nothing in team fights you can buy this, invoke ghost walk, and push like your life depends on it then turn invisible and run the **** out when anyone comes in view. BKB is one of the most situational items ever on invoker, you may never buy it but i put it on every build i make because it can needed. You will only buy it if every team fight they focus you with all their stuns and nukes and kill you before you can even ghost walk away, usually this only happens if you are very good and get many early kills while ganking or if you **** talk them and they get so angry they forget your on a team of five. A skadi can help if you're having problems chasing or if you need help because it gives you second most hp gain behind heart and the stats are all around useful.
If the game ends up lasting long enough or you become a rich invoker because of your hopefully successful ganks the it might be a good idea to pick up B.O.T and get a euls or sheep stick for your last item. Not really much to say about these they're pretty self explanatory although you can change up your last item for more than just these things and can sell your bottle for both once you're really late in the game. The blink dagger can be useful as well for initiating and such or for solo pick offs. An Atos can be helpful as well if you find yourself dying a lot or needing a more reliable escape or initiate this can be a viable item which I personally love.
As I've mentioned and i hope you know by now this build is a Quas-Wex build and is leveled accordingly. I like to get the first 3 levels possible of Quas that i can of course leveling invoke and Wex in between. Then move into maxing Wex, respectively leveling invoke when possible. At level 9 you can either put a point into Exort to unlock the rest of your spells or upgrading quas again for more regen, i prefer unlocking Exort but those spells do hardly anything with one level so some prefer to just make their Quas-Wex play stronger with Quas. after Wex is maxed you want to focus on Exort and take your last level of invoke when available. Finishing off the build with maxing the rest of your Quas.
Quas is your first of three stat modifiers you can chose from to summon. It comes with passive strength bonus, and passive health bonus when invoked
Wex is your second passive summon. It has a passive agi bonus and a passive movement and attack speed bonus when invoked.
Your third and final summon is Exort. Exorts passive is bonus int, while its active passive is attack damage bonus
Invoke is carls ulti and is a very unique one. It allows him to have 10 different spells. He can activate 1 at a time and 2 after invoke is level two, and gains one based on his current summons everytime he uses invoke. and every spell has a separate cooldown so you can get them all off in one team fight if you have the mana and ulti stick to change them fast enough. This is what gives invoker such a huge skill cap because he has the ability to be as good as you can play him.
Cold Snap(Quas Quas Quas)
Cold Snap is an effect that last 3 / 3.5 / 4 / 4.5 / 5 / 5.5 / 6 second based on Quas levels and on every hit while a target is effected gets mini stunned for .4 seconds and hurt for an extra 30 damage and has an initial effect of 60 damage and the bash. It also has a small wait in between possible stuns that is 0.7715 / 0.7430 / 0.7145 / 0.6860 / 0.6575 / 0.6290 / 0.6005 of a second based on Quas again
Ghost Walk(Quas Quas Wex)
ghost walk is a invis ability, although when using it to gank be careful because it will slow enemy units in a 400 aoe based on your Quas 20% / 25% / 30% / 35% / 40% / 45% / 50%. It also slows you or speeds you up based on Wex -30% / -20% / -10% / 0% / 10% / 20% / 30%. Mainly you will want to use this to pass were wards might be when going for a gank or to escape, it is not ideal for initiation.
Ice Wall(Quas Quas Exort)
Ice wall can be a very useful spell or one that does nothing all game depending on whether or not you can land it. It places a wall of ice directly in front of you that slows based on Quas 20% / 40% / 60% / 80% / 100% / 120% / 140% and the duration is also based on Quas 3 / 4.5 / 6 / 7.5 / 9 / 10.5 / 12. It also does 6 / 12 / 18 / 24 / 30 / 36 / 42 based on Exort levels. used well you can place this as a blockade in lane from behind the enemies and sandwich them in with a frontal rush from your team, or you can save lives by placing it as an escape mechanism.
Emp(Wex Wex Wex)
Emp is a delayed mana burn and nuke. 2.6 seconds after being placed it explodes draining 100 / 175 / 250 / 325 / 400 / 475 / 550 based on Wex levels and damages the enemy and restores your mana for half the amount of mana burned
Tornado(Wex Wex Quas)
Tornado is exactly what it sounds a tornado that goes for a range of 800 / 1200 / 1600 / 2000 / 2400 / 2800 / 3200 based on Wex and throws anything it hits into the air for 0.8 / 1.1 / 1.4 / 1.7 / 2.0 / 2.3 / 2.5 seconds based on Quas. It purges some buffs as well as doing 70 + 15 * (2 * Level of Wex + Level of Quas) damage its max damage that can occur is 385. Tornado also gives vision along its path, and does not apply damage right after the lift ends so watch out for blinks because they have a small window where they still can afterwards. This is an especially useful ability for ganks but can be difficult to land at times so it's good to practice this one in bot matches.
With all the power Invoker has in dota its easy to forget how simple he is to counter and that you should never instalock him. Do not play him against Silencer, Pugna, Doom, Outworld Devourer, or nyx assassin. Also if you find that someone on their team has acquired an Orchid I'd advise not initiating yourself and let someone who is more capable while silenced do it that way you can contribute because with out his spells carl is just another plain old man.
As invoker one thing you need to do at all times is have very good awareness of the map and enemy team. It is very helpful to be able to use sunstrike if you actually know when people are low on health or know when is a good opportunity to gank. Try to get your teammates to communicate as well so you can be able to be more aware without having to be watching everywhere.
Above all try to have fun and be nice to your fellow team members it doesn't help at all to get salty and harass your teammates if you or them are doing bad. Try not to call them a noops or cyka and instead maybe suggest ways that you can approach team battles. Although it may annoy some to try helping so if people get mad because of that to stop using chat and just use the chat wheel to keep them informed and stay neutral, it really helps to stay calm just try it.