You can use the Freeform Spells rules note in the Magic Alteration. By default, they cannot deal damage or inflict conditions, and numerically I would personally make them either work like Aid, except scaling with your Special Proficiency, or grant resistance/other benefit equal to the Special Rank of the caster (like casting an anti-lightning spell).
Duration-wise, if it's primarily combat-focused (like resistances or granting strength), I would make them last 3 turns (i.e an Active Effect 3), and if they're more exploration-focused (protect against Exposure, waterwalking, waterbreathing etc), I would make them last until Refresh.
If they want to cast something that's more "debuff"-oriented, you can increase the Strain or Action cost to cast it from the default 3 I lay out to break the "don't inflict conditions" limitation. I did try to make it so that most conditions are achievable without magic, but spells can obviously be tinkered with Range, AoE, etc.