If you happen to wander across sweet Alice during her travels in Wonderland and she should happen to flash red, white, and red all over, you're probably going to die. This is Hysteria.
Similar to the powerful effects of the Rage Box from American McGee's Alice, the Hysteria power in Alice: Madness Returns infuses our hopeless heroine the power to destroy her psychological demons when all hope seems lost. It's a way to pull her back from the brink of death, while pushing her enemies over it in spectacular fashion.
Save your hysterics for when Alice: Madness Returns comes calling on PC, PlayStation 3, and Xbox 360 on June 14. You'll need them.