Oh definitely. It went over very well. I let them all know before they chose to fight that they felt Pharasma pull her boon back temporarily for the fight (she wasn't getting involved with that) and that if they died their character was gone forever. )I removed the part in the adventure about players being able to come back after the sacrifice). The players went in with full knowledge of the consequences, and if they hadn't defeated him in that round, the bloodrager, and probably the bard would have had to switch to their sidhedron hero characters.
I the part about his death Leaving a scar on the ground in the same manner as Alaznists wounds really gave them pause and made them wonder if they made the right choice