At work so I didn't watch the vid. Is it Crota HM? Because on NM there really is no need for a rocket launcher. The first few times we ever did Crota NM, we did it with mostly Ice Breakers and VoCs. Back in tha day when we used to call out Crota's shield in percentage for the swordbearer. With rockets, I'm pretty sure you only need 2 Hunger of crota shots and maybe some IB shots to knock him down actually.
Now Crota HM is generally a different story. Don't need Gjallarhorn/Hunger of Crota necessarily, but a tracking rocket is still the best option. If he solo'ed Crota without either on HM, that's pretty impressive.
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