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Now the WBB rules state that you dont get WBB if instant killed or denied an armour save in melee.
Now what happens with wraiths?
Eg.: A genestealer causes a rending hit against a wraith, it still gets its invulnerable save but it fails this. Does it still get WBB?
Wraiths have an Inv save, so surely they get WBB from nearly everything, right?
NO, WBB is not the same as their invulnerable save. So no save CC weapons and double toughness can negate WBB still. People think because they have an invul they get an invul WBB, that is NOT the case.
So in essence, YES rending in CC would negate your WBB. However rending if something was shooting (assault cannon) would not negate WBB.
"There is only do, or do not. There is no try." - Yoda
Run your units of Wraiths together with a Destroyer Lord that has a res orb