Most of those issues can be resolved by making it a different Timelord that is going through the regenerations.
Actually, I can totally see the Docter showing up during a Necron attack and the entire force stopping dead and teleporting away or otherwise fleeing in what for anyone else would be a blind panic... Much confusion reigns and several of the Necron are unmoving after he pointed a magic wand at them. The Space Marines are all huffy as the Emperor left explicit instructions that that should such a thing occur they owe him a pint.
Meanwhile, there is a ship of Twisted Chaos traveling the Warp Sea that has a dread cargo entirely composed of hand written hate mail from a certain avian plotter.
Actually, I can totally see the Docter showing up during a Necron attack and the entire force stopping dead and teleporting away or otherwise fleeing in what for anyone else would be a blind panic... Much confusion reigns and several of the Necron are unmoving after he pointed a magic wand at them. The Space Marines are all huffy as the Emperor left explicit instructions that that should such a thing occur they owe him a pint.
Meanwhile, there is a ship of Twisted Chaos traveling the Warp Sea that has a dread cargo entirely composed of hand written hate mail from a certain avian plotter.