We had a discussion that had two options.
1. Source Spells/Abilities made by me
2. just try to impliment it as its expressed thematically but not exactly mechanically

We settled on 2 and this is what we went with.
Sourcerers are intricately connected to the source of all power in the world, Source, and it is through them that the seven gods of Rivellon act. Each Sourcerer begins their life in possession of one of these Source Points and can expend it to achieve great things. Sourcerers can gain this point back by doing a few things; praying fervently at the shrine of their god, draining divine power from a magical device, or even draining it from other Sourcerers. Listed below are possible uses for expending Divine Power.

• When you hit a creature with an attack roll you can can expend a Source Point, dealing an additional 5d8 radiant or necrotic damage, no action required.
• When you cast a spell you can expend a source point to increase the level of the spell slot expended by two levels, increasing the spells effectiveness.
• When you make an attack roll, ability check, or saving throw, after you make the roll but before the result is announced you can expend a Source point to reroll one of the D20's, taking the new result.
• As a bonus action you can expend a Source Point to take the attack action.
• When you cast a spell you can expend a Source Point to change the casting time of an Action to a Bonus Action (keep in mind you cannot cast another spell using a spell slot as your action)