The hypercharge has multiple effects:

-Unlocks HeatBlast
-Unlocks Auto Cross Bow

Heatblast is a GCD (Weaponskill) at the fastest speed that also reduce Gauss round cooldown by 15s, later on it will also reduce Ricochet cooldown by 15s.
Auto Cross Bow is also a GCD at the fastest speed but as an AoE.

MCH also has a skill named Wildfire, a bomb that explodes after 10 seconds which potency increase everytime you hit it with a Weaponskill.
You guess it, you are supposed to use Wildfire, then Hypercharge and spam the fast Weaponskills.


In the endgame, you'll often use Hypercharge to spam Heatblast -> Gauss Round/Ricochet -> Heatblast -> Gauss Round/Ricochet -> Heatblast -> Gauss Round/Ricochet -> and so on...

Other than that, Hypercharge is all about damages.