My 2 favorites are Memory of Lucid Dreams and Blood of the Enemy
Reasons and Usage:
Memory of Lucid Dreams (in PvP)
You use the essense and activate Immolation Aura
Keep spaming chaos strike for the entire duration but DONT MOVE to catch orbs from demonic Appetite
Once the buff ends, you move to catch orbs and keep spaming chaos strikes.
You are literally able to spam chaos strikes for 25 seconds straight.
Is game changing and awesome in PvP
Blood of the Enemy (in PvP)
You bind the essense to a power steroid trinket with a macro.
You use AoE stun...Essense...Fel Barrage...
Watch all the enemies around you melt with Fel Barrage crits insane AoE damage in PvP.