Maybe if we're lucky u/Mark_GGG will be willing to help us out. My impression was that Spellslinger just added the final damage of your wand to the spell as a flat number (in this case the 74-181 on Obliteration), not the mods themselves.
If you look at a wand (or any weapon) item, in the base properties section above the mods and requirements, it will show that weapon's damage values. If you equip that weapon, those values are your base attack damage (for that hand). Those numbers are what Spellslinger cares about. Local modifiers can affect those numbers (making the physical damage display in blue if modified, and adding values for other damage types).