the crystal harry has molly use i turncoat has a mobile ward effect that becomes immobile(ish) one activated. He explains to Ebeneezer the amount of work he put into making it work "without a threshold' towards the end of the book and it was pretty significant. Theoretically you could have a ward that doesn't require a threshold, it just lacks clear rules and would take a gm call for difficulty. Protective spells and wards are very different things in dfrpg, wording is important