How do you explain this rule (Instant death effect on combat resolution)

[Defenestratus]

Casual game at the local GW this past weekend led to a small disagreement between my opponent and I about something that I've always played as second nature since the instant death rule was around.

During combat, my wraithknight charged a squad of deathmarks with Zandrek attached and in front. During the fight subphase, before he was able to pile in, I instantgibbed Zandrek in combat. The deathmarks couldn't hurt T8 so combat was over. In my book, he had to take a morale check at -3 since Zandrek had his full 3 wounds when he died. But he claimed that since I only did 1 wound with the instant death rule, his morale check was only at -1. I couldn't find anything in the combat resolution rules or the instant death rule that would strictly specify the modifier as the total number of wounds that he lost combat by (which he still claimed was only one).

I know i'm right, but I just couldn't articulate it properly.

[thepolytheist]

Page 52 of the BRB, last paragraph, confirms that you are correct. You include all wounds lost by a model killed by Instant Death. (The Morale portion is on 57.)

[Defenestratus]

Page 52 of the BRB, last paragraph, confirms that you are correct. You include all wounds lost by a model killed by Instant Death. (The Morale portion is on 57.)

Can't believe I missed that. Thank You