Potion-like multi-item. As in, several slots that are different enchanted abilities in one physical item sort of like having a necklace where every stone is separately enchanted. It requires a Lore of 5 and +1 potion frequencey and 3 potion slots.
1st slot is 10 shift "potion" that applies 3 aspects with two uses.
2nd slot is a 10 shift "potion" that creates a ward - first use is a 10-shift Ward, second use benefits on activation by said 3 aspects above so its strength is pushed to 16.
3rd slot is a 10-shift landmine that activates if the wards are breached. First use is a Weapon 8 zone-wide attack blasting whoever breached the Wards. Second use benefits from 3 aspects on activation, being a Weapon 8 attack on 4 zones, including the zone of whoever breached the Wards.
Yep, it is a weird idea and it kind of pushes the limits of potions but it took 6 months for Harry to make it while a normal potion takes a couple of hours. I am assuming here that Harry invoked aspects during creation so he pushed the potion strength from the normal 5 to the maximum of 10 for him. And yeah, it is a scarily powerful defense - as it should, since the Naagloshi could not breach it.