Spell lists cover the broad range of spell rituals that empower casters, but the basic effects of rudimentary magic remain the same as in typical 5E rules. As such, spell casters still gain access to a number of Cantrips based on their chosen professions.
Cantrips can be cast at any time, require casting checks just like normal spells, and have all the same component requirements as any other spell for a profession. Channeling cantrips come from the Cleric and Druid spell lists. Essence cantrips come from the Wizard, Sorcerer, and Warlock spell lists. Mentalism cantrips come from the Bard and Warlock spell lists.
They cost no Power Points to cast and can be cast at will, even if the caster has zero pow remaining.