Consumable: Vanguard Tactician Token
Proof of valor displayed in defense of the city.
Obtained: You can obtain these from doing Strikes in the Strike Playlist. Completing a strike will net you 3 of these Vanguard Tactician Tokens.
Usage: Redeem with Commander Zavala in the Tower to increase Reputation. Handing him 20 Vanguard Tactician Tokens will give you a Vanguard Tactician Engram that contains purple legendary gear. You get access to Zavala in the Tower after beating the story.
This is where you find Zavala in The Tower to trade in the Vanguard Tactician Tokens: