[Suggestion] Invocation Support - Only Cast Once

Chayula Monk - 62
Act 3 Cruel

Context
My current basic combo for clearing looks like:
- Shattering Palm
- Elemental Invocation -> Hexblast with Blasphemy (triggers Shattering Palm Explosion)
- Ice Strike (anything still standing)

Problem
I run out of mana largely due to the fact that I regularly gain too much energy and have to cast 2, 3, or sometimes 4 hexblasts when I only want to cast it once.

Suggestion
I want a Support Gem, which will force invocations to only cast once, even if they have enough energy to cast multiple times, keeping leftover energy in reserve.

This would let me use it more like an ammo system which I have to charge up and can then use one shot at a time while keeping some shots in reserve. The Max Energy then allows me to hold more spells in reserve.

Conclusion
I think this would be a really fun way to use invocations rather than just being forced to dump the entire magazine of spells on use (granted there are good use cases for that too).

It also allows for a more controlled playstyle that isn't so focused on just spamming spells for max dps and instead cares about careful combo management. I also believe this is aligned to the strategic direction that GGG is taking the game.