jade tulip
Fantastic Chorus' Sorrow Sonata was an interesting debuff (especially when combined with our server's set of Gachapon gear that had an enhancing Set Effect) because it encouraged Party play.
Everyone in the Party was encouraged to engage with it to spread the debuff as far as possible and it was fairly easy to slot it in to a rotation due to it being a Bard Skill.
Seeing it lose most of its power in favor of reallocating its strength elsewhere is sad. I don't know how many people agree with me but it was one of the more interesting and visible ways you could debuff an enemy.
crimson sleet
fathom berry
dire lake
deep vortex