A character can Guard a Link, another Character, or an item within their Zone.
Guarding Characters
If a character is guarded they receive 1 Cover for each character guarding them.
Guarding Links and Items
If a Link or item is guarded, the difficulty of any Test involving it is increased by one.
If that test has no set difficulty, it is 7.
When guarding a link, characters in the linked zone can attack you as if you were in the same zone as them.
Example
Normally Moving through a link during initiative is a Knack Test, with no set difficulty. If someone is guarding that link, the test now has a difficulty of 7. Failing the test prevents moving.