Unkillable Electro Priests?

So they come with 5+ invulnerable and a 5+ feel no pain Equivalent. Does the forge world dogma 'Refusal to yield' (on a 6 dont lose a wound) also occur after this?

On top of this, can you take the Engiseer commander and use 'repair artisan' to reroll on 1s for the FNP save and the forge world dogma save?

If so these guys are surviving everything