In the anime, the deaths of the remaining X-Laws. Miina's was probably the most heart-wrenching of all.
Miina: (icicle spears rain down but Miina calmly turns to face Lyserg) "You are so kind Lyserg. We have always viewed compassion as a weakness, but perhaps through your kindness you will find a way to achieve what we X-Laws could not. Stop looking for people to follow Lyserg and learn to trust your own heart." (she's then skewered by the icicle spears)