What is the best way to cast spells with different mana point values?

I’ve recently created a mana/MP system, which works in a similar, if not the same way as a health system. I already know how to make projectiles and have made a few spells to be cast from the player.

My problem is trying to find the best way of telling the mana system what the incoming mana value is and then firing a specific spell. However I want more than one spell.

Do I store the mana cost of a spell within the projectile? (Using a BPI or Cast to Player using maths such as: “If the incoming mana value is higher than the current mana value, then do not cast, however if incoming mana is less or equal to the current mana, cast the spell”)

Would I need to make an array or inventory?

As you can tell, I’m not much of a coder and I’m using Blueprint and hope to achieve the end result in blueprint.

I’ve currently made a custom event in my Character Blueprint to depletes mana. Whether this is the best way to go about depleting mana, I have no idea. Any help is welcome!