Thornveil Sunsinger
Exotic Armor: Apotheosis Veil
Exotic Weapon: Thorn
Subclass: Sunsinger
Necessary Subclass Skills: Fusion Grenades, Radiant Skin, Viking Funeral, Touch of Flame
Legendary Complements: 77 Wizard, The Swarm/Unfriendly Giant, Eclipse Maw IV (gauntlets)
Legendary Replacements: The Devil You Know
Notes: This is a pure gimmick build and isn't likely to have much use outside the Crucible, but holy hell do I bet it is fun inside. This is the max-DoT-infuriation build. While unfortunately the effects do not stack (credit to Diablohead testing... I wonder if they tried this out and realized it was too OP after 5 minutes and changed them not to stack), you will still have three ways to cause a DoT effect: hitting with your primary weapon, Scorch melee, and any grenade contact. The latter two will cause a longer and stronger DoT while the former can be applied at will at long range. So in addition to your standard shots with Thorn, every time you hit with Scorch (causing a DoT) you'll get a flame shield and decrease your grenade cooldown so that you can throw more (causing DoTs). Anyone you don't kill the way you intend to is extremely likely to die to the DoT effect shortly after.. this will be a postmortem powerhouse. Speaking of which, you'll want to (hard as it may be) stay away from Fireborn on this one in favor of Radiant Skin- popping your Super heals you from the helm's effect, so use it when low on health rather than after death.
Note that while all of the skills and Legendary chest mentioned are for Sunsingers, the helm is actually subclass agnostic, and the basic concept with Thorn's DoT in PvP could be used with a STR-heavy Surge melee build to keep Thorn's reload times down instead of using the Sunsinger for other ways to cause DoTs. There's probably a more effective gimmick Thorn build with a Voidwalker-specific Exotic though.