Wildcards in Black Ops Cold War can be thought of as an extra perk but far more powerful. Nothing in the class needs to be sacrificed in order to equip a Wildcard. It's a free slot, but only one Wildcard can be equipped at a time.
In essence, they provide an excess of one aspect within a class. That could be additional perks or additional attachments. So far, the perk options are the best.
Wildcards in Black Ops Cold War
There are currently four Wildcards in Black Ops Cold War that each have their own powerful bonuses.
Danger Close: This is the first Wildcard unlocked in Black Ops Cold War. It's based on starting each life with as much additional equipment as possible.
Extra lethal and tactical equipment pieces are provided as a base, and players start with additional ammo. All the extra equipment can come in clutch sometimes, but Danger Close is likely the weakest of the Wildcard options.
Law Breaker: The first of the two perk based Wildcards, Law Breaker is essentially the classic Overkill perk with added benefits. Any weapon class can be equipped in both primary and secondary weapon slots.
A second bonus allows any perk within any category to be chosen. That means players could equip three yellow perks if they wanted to.
Gunfighter: Using Gunfighter seems like the most fun or powerful of the Wildcards on paper. It simply lets players equip an attachment from each category on their primary weapons. That means eight attachments in total on primary weapons.
It sounds great, and can be a lot of fun, but it's not worth it to have all those attachments over far better perks. In most cases, it's very easy to do without those three additional attachments.
Perk Greed: For anyone not needing two primary weapons, perk greed is likely the best Wildcard option in Black Ops Cold War. It allows an extra perk to be equipped in each category, and that's six perks in total.
The best part of the Wildcard is being able to equip Tac Mask, Flak Jacket, Ghost, and Ninja, all at the same time.
In general, choosing either Perk Greed or Law Breaker is the best bet for a great Wildcard pick in Black Ops Cold War.