While I was playing destiny I was thinking about GoT and so then I noticed something guardians are future medieval warriors.
Warlock=Mage
Hunter=Ranger or spy
Titan=Knight
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Dude, it's basic RPG tropes. Hunters are the rogue build, Warlocks are the Mage build, Titans are the warrior build. It's literally the building block of every RPG/MMO class system.