https://www.polygon.com/2017/12/21/16808242/destiny-2-bug-infinite-nova-bomb-bungie

Another week, another Destiny 2 bug. This time, it’s an issue affecting the player-versus-player Crucible: Guardians have discovered a glitch allowing Voidwalker Warlocks to fire their super attack as often as they want.

The bug exists only in the Crucible’s Mayhem gametype, which Destiny 2 developer Bungie revived for The Dawning, the game’s holiday event. That’s because cooldowns for grenades, class abilities and super abilities are greatly reduced in Mayhem — and the glitch involves both the Voidwalker grenade and super.