When it was originally released, Destiny featured a little thing called Vanguard Streak, which you would get for running multiple playlist strikes in a row without returning to orbit. This modifier didn’t really do much for players and offered little benefit.
Since the release of The Taken King and the 2.0 update, the Vanguard Streak has gotten something of an overhaul. The streak bonus starts after a single strike on the strike playlist and continues as you keep playing, provided you don’t leave to do something else (like return to the tower) or get a network error. The modifier improves the gains to your Vanguard reputation and increases the chances of receiving legendary engrams from strike bosses.
Additionally, there is a new Heroic Strike playlist with a higher recommended Light level that raises the difficulty. You’ll encounter more enemies and shielded Ultras during these strikes.
Completing the strike for the first time after each weekly reset guarantees you a Legendary engram. The first three completions of the strike will give you 10 Legendary Marks each. This is account-wide, so you won’t be able to grind additional Legendary Marks with the other characters on your account.
Beyond the weekly reward, performing Heroic Strikes does not increase your chances of getting legendary engrams from boss kills.
After completing three Weekly Heroic Strikes for the guaranteed Legendary engram and 30 Legendary Marks, you’ll want to go back to playing on the regular Vanguard Strike playlist. You’ll go through them much faster.
Furthermore, given how the matchmaker works, it may be difficult to keep your streak bonus in the Heroic Strike playlist if players drop out (due to the difficulty) and you’re unable to find replacements.
Be sure to check out our guides on the fastest way to earn Legendary Marks, Infusing weapons and armor, the fastest way to raise your light level, and how the Exotic Blueprint system works. You can also find our guide on locating every Calcified Fragment in the game.