how do I use these packs and request in halo 5?

[666 ReVeNGe 666]

I'm so confused

 

[Tic Tac T O]

packs can contain REQ cards, armor, helmets, visor colors, stances, assassinations, or weapon skins. REQ cards are only used in Warzone and Warzone Assault multiplayer modes. As you play through the match, your REQ level goes up allowing you to choose one of those cards.

everything else I mentioned in the packs are found in the customization menu to be used anywhere in multiplayer