"Why are you banging your head against the wall?'cause it feels sooooo good when I stop..."
Wards can be built without thresholds, they just don't last very long. Until the next sunrise, probably, since that's the usual point where wards are degraded.
It’s intended to protect an area—usually a homeor sanctum—from physical or magical intrusion.
By default, a ward lasts until the next sunriseunless you add complexity to make it last longer
Wards don’t have a “scale” concern, the waythat veils do, and they cannot move. They arealmost always tied to a particular place’s naturalthresholds—think of them as a super-boostedimmune system—so they are limited by the sizeof that threshold. Without a threshold they canonly be set up to cover a small area at most—usually a point of transition such as a doorwayor intersection.
Then how did the Merlin and the Gatekeeper set up the mega-ward that stopped the entire Red Court/Outsider army in Dead Beat?
Can you use the Eastern philosophy "My body is a temple" to put a ward on yourself?
Anyway, it was probably less a "ward", mechanically speaking, more a giant powerful block against movement/attack from the Reds. And it was just called a ward.
Without a threshold they canonly be set up to cover a small area at most—usually a point of transition such as a doorwayor intersection.
Small area is about a zone. See the portable Ward Harry gave to Molly in Turn Coat for example - it was a room sized sphere.