What episode is this(3)?

Paige casts a protection spell on an Innocent when Sirk, a Demon-Mortal Hybrid, tries to kill him to become fully demon. The spell goes wrong and the Innocent can't die. The spell blocks all deaths, and the 天使 of Death recruits Piper to catch up the damage the spell has done.

ay the name of the episode and also what season it's in to win 10 支持 - only 1st correct answer gets the props!!!!:)