Invoker no matter how hard certain spells get nerfed will continue to see play at great success.

A toolbox is a valuable tool to have, the ability to pick and choose what tool you need at any given time. But toolboxes generally have set rules to not make them objectively overpowered and they are as follows:

1) Having to choose which tool you want

Toolboxes are generally heavily resource restricted. When you can literally throw the toolbox at the enemy there is no restriction, you just have access to 9 spells.

Even if you nerf 4 of his spells to be bad, ok so what he has 5 spells and 4 bad spells that he tosses out for free.

This hero suffers no mana problems mid to late game and invoke has a .9 second cooldown. You can literally just throw out every spell and suffer no negative.

There's no option other than gating invoke. Invoke needs to be a much much higher cooldown to where the hero can pick 3, maybe 4 spells to use in a fight. That alone is already very strong.

2) The counter to toolbox needs to be consistent

It's currently nearly impossible to counter this hero properly. If you bring dispels, he has multiple spells that can't be dispelled or are unaffected. If you bring bkb, cataclysm pierces. If you bring dive, he has cyclone and invisibility.

There should be ONE answer to this hero that answers everything he can throw at you. None of this sectioned dispel some bkb some dive some.

3) The spells cannot be insanely powerful at any point

The whole point of jack of all trades master of none is that he's a master of none. If you are a master of some you get access to 3 incredibly power spells and 6 mediocre ones.

As long as Invoker breaks these core principals this hero will never leave pro and high mmr play, ever.