There is four kinds of spellbuff base spellbuff and faith, int and luck(only mangrubb staff) scaling spellbuff. The base spellbuff seems to always be 100 or a x1 damage multiplier if you met any int and faith recuirements. The other three scale with your stats.
You can only see the total spellbuff but as a rule miracles only scale with faith spellbuff, sorcery with int spellbuff and pyromancies with both. NOTE the whole listed spellbuff is not always used.
Certain catalysts can give non standard scaling to direct damage spells. Other spells relying on spellbuff notibly weapon buffs and direct heals are never affected.
The following catalysts provide non standard buff scaling:
Izalifh staff, Caitha's chime, Sunless talisman -- provide both int and faith scaling to dark miracles and sorceries.
Crystal chime -- provides both int and faith scaling to magic sorceries and lightning miracles.
Deacon staff, Golden ritual spear, mangrubb staff -- provides faith/luck scaling to both dark and magic sorceries.
As a rule off tumb you should avoid multi scaling unless you are doing a pyro/hexer build and then make sure that your spells are supported by the catalyst hope this helps. :)