Phalanx is a Grimoire card from the original Destiny (Destiny 1), found under Enemies → Cabal. Grimoire cards held most of the game's lore and were read on Bungie.net and in the companion app, not in the game itself.
Card text
Phalanx soldiers carry massive shields, used for both attack and defense. While this protection is nearly impenetrable, clever opponents can bait the Phalanx or sneak shots around the shield.
Grimoire text written by Bungie, shown as it appears in the Destiny 1 game files.