Hextech needs reworking
In hextech's current state, I don't believe it is fun for anyone. I suggest reworking the buff entirely, or reducing the disable time to 5 seconds for the 2 hextech champion synergy. When one is in the mid game, and only has 2-4 items, the hextech disable makes fights nearly impossible when stacking items. At this point, it's very hard to make it to late game, where items are spread across more units due to a higher number of items.
Nobody utilizes the 4 champion synergy hextech combo because of the terrible synergy between hextech units; it's not worth the reward. Honestly, I believe that reworking the class to be a buff instead of a debuff for the enemy team to be a better choice. For example, the buff could be to give all items double or more of their base stats at full synergy, and at 2 champion synergy, to buff one random stat on the item. Making it a buff would be much more appealing to everyone.