I have yet to test this outside of dungeons, I don't imagine why it wouldn't work. Feel free to test. If it does work, would probably be very OP on certain AoE debuffs in HFC, etc.
Anyways.
With the Spell Reflect Glyph for Grounding Totem, you're able to reflect AoE damage debuffs to the original caster. Same goes for Mirrored Blades Glyph? (Not sure of name of Glyph, any Hunter should know.)
I'll go through the Dungeons that you are able to do this, and how to.
Grimrail Depot:
1st Boss.
You are able to reflect his Missile Barrage.
5-10k Fire damage per tick. Has ramp up damage which is done by Rocketspark while on top of Boxes or when Brute is dead. Place Totem as boss leaps up onto the boxes and it'll reflect the damage for the duration of Grounding totem, its guranteed atleast 150k damage. That's incredible for one GCD in a CM.
Gromkar Gunners and their pesky Shrapnel Blast.
8-12k per tick. must be standing in the cone for it to work while grounding totem is down. Player still takes damage. Does not apply the DoT.
2nd Boss
You are able to reflect Slag Blast.
2k fire Damage per tick, + 30% Fire damage taken per stack. This can stack up to 10 times, allowing him to be one shot by homing shells. This can be reached quickly with more than 1 person standing in Slag Blast at a time with Grounding Totem down. (Deterrence works here as well.)
3rd Boss
Skylord Tovra
Diffused energy.
1k dmg damage per stack, max 4 stacks. Damage for this is crap. The main use of this is that people who stand in Diffused Energy with Grounding Totem down will not have to move for the duration as they will not take damage from it.
Bloodmaul Slag Mines
Bloodmaul Flamespeaker and their Channel Flames. 35k DoT left on the mobs, someone must be standing in the cone for the effect to trigger. Last while a player is in the cone or until Ground Totem duration is up. (Works with Deterrence)
Iron Docks
Makogg Emberblade and Lava Sweep.
100k fire damage per tick, walk inside move back out while Grounding Totem is down. Applies dot to Makogg. (Works with Deterrence.)
Shadowmoon Burial Grounds
Nhallish and his Void Devastation.
50k Shadow damage per tick, move in the shadow pool after his formed and move out to apply a permanent DoT to boss.
Ner'zhul and Ritual of Bones.
150k Shadow damage to Skeletons, reflects the black S**t that trails them back onto them. 2 shots them or simply allows you to not have to move.
Skyreach
Ranjit and Windwall/4Winds
50k Nature Damage per tick, move into the Wall with Totem down, move out Applies DoT.
Everbloom
Archmage Sol and her Frozen Rain.
30k frost damage per tick, stand inside it for Damage, move out to stop.
Earthshaper Telu and Bramble Patch.
Once Bramble Patch forms, drop Totem, move in, move out applies Debuff.
Enjoy.