While many folks have been envisioning a myriad of gates and guards and devices for opening and closing of portals, both magical and mundane, let's take a quick look at wards...
And, for a bit of inspiration, how about a story perhaps familiar to many of us. The Passover.
(Disclaimer: I'm not Jewish or any sort of Biblical scholar. I know the Passover via the book of Exodus (and that movie with the former head of the NRA), so if I get anything incorrect, please feel free to correct me. Additionally, I don't think that the stories and mythologies of the Bible get a lot of Appendix N love...)
Most familiarly, the Passover is associated with the 10th Plague brought upon the Egyptians during Moses' petitions to free the Israelites. To recall, any home not properly warded would be visited by the Angel of Death, who would take the life of firstborn children. Any warded home would be 'passed over' and left unmolested.
Here is the evocative scene from 'The Prince of Egypt'...
The ritual and 'material components' of the warding are very specific: "3 Speak to all the congregation of Israel, saying, 'On the tenth of this month they are each one to take a lamb for themselves, according to their fathers' households, a lamb for each household. 4 Now if the household is too small for a lamb, then he and his neighbor nearest to his house are to take one according to the number of persons in them; according to what each man should eat, you are to divide the lamb. 5 Your lamb shall be an unblemished male a year old; you may take it from the sheep or from the goats. 6 You shall keep it until the fourteenth day of the same month, then the whole assembly of the congregation of Israel is to kill it at twilight. 7 Moreover, they shall take some of the blood and put it on the two doorposts and on the lintel of the houses in which they eat it. 8 They shall eat the flesh that same night, roasted with fire, and they shall eat it with unleavened bread and bitter herbs. 9 Do not eat any of it raw or boiled at all with water, but rather roasted with fire, both its head and its legs along with its entrails. 10 And you shall not leave any of it over until morning, but whatever is left of it until morning, you shall burn with fire. 11 Now you shall eat it in this manner: with your loins girded, your sandals on your feet, and your staff in your hand; and you shall eat it in haste-- it is the LORD'S Passover.…"
According to my half-vast research of wikipedia and other such hallowed sources, the Passover actually predates the Exodus as a springtime warding or protection rite, and the prescription includes using a hyssop bough for painting the blood onto the lintel.
Not having read this since teen Bible study, something interesting that I hadn't noted before is that the blood is both spread on the lintel, and consumed (along with the meat of the sacrificial lamb), thus extending or fortifying the protection from the portal to the inhabitant as well, as sort of redundancy (or perhaps an early form of 2-step authentication).
Now, this isn't a unique traditional warding by any stretch of the imagination - many cultures have wards of one sort or another.
A quick summary - a sacrificial animal meeting particular criteria, its blood both spread on the door lintel and consumed, and its meat cooked in a specific way and consumed with accompanying foodstuffs, all while wearing your travelling clothes. Oh yeah, and don't go outside...
So to create some veracity in a game/story environment, perhaps add the necessity of collecting rare components or knowledge as prerequisites for the ward itself... Building tension and time-pressure before the approach of a physical, magical, or spiritual threat could create some excellent game moments or opportunities. Likewise, it can add to the living nature of the cultures or systems in place in the game world.
"Ok, Dingwall, here's what you need to do to protect your castle from the Wight-bear. Take the bark from the foo-tree collected under the gibbous moon, mash it into a poultice with some tapioca using a rubber-tipped arrow. Wipe it on the portcullis with a Backscratcher +1, and dab the rest under your armpits, as well as those of everyone in your household. Eat of the Sacred Chicken Pot Pie of Swänsön. Oh yeah, all while wearing a thneed."