Oracle Text

Damage that would be dealt by Excruciator can't be prevented.

Card Rulings

10/1/2005 An effect may redirect Excruciator’s damage.
10/1/2005 Excruciator can deal damage to creatures with protection from red. (It can’t block creatures with protection from red, though.)
10/1/2005 Damage prevention shields that would prevent this damage aren’t used up and they stick around for the next time something would deal damage.
10/1/2005 A creature dealt lethal damage by Excruciator can be regenerated.
10/1/2005 Replacement effects that don’t use the word “prevent” can replace Excruciator’s damage with something else. See Phytohydra and Szadek, Lord of Secrets, for example.