Personally, I just started trolling people in the Looking Glass Knight boss fight by being summoned as a dark spirit. I then continuously harass them with the force miracle so the LGK beats them to a pulp, if I run out of force, I go into the Lightning Round. And by lightning round, I mean spamming the shit out of Blinding Bolt and then using R2 with my Dragonslayer Spear when they run to heal.
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Too bad they don't have a ring that makes you look like the phantom that appears at a blood stain. Imagine the shit you could do with that.