Well, I would say that the Royal Guard putting a group together would be the best way to get most of them together. It's nice and neat, and doesn't require every character to have a different reason for being in the group.
Rolf would make sense to summon, he's one of what must be just a handful of necromancers who are in good standing in the kingdom. Iestyn is, as you said, likely already working for the Royal Guard. We won't know about Ved until his bio gets finished.
Rolf is a little short, very thin and looks a little sick most of the time. His hair has already lost all color, and is permanently silver white. He's dressed warmly, usually has a staff with him, and smells of sandal wood.
Personality: A shockingly congenial person. Those who know him by trade first are surprised by his demeanor, and those who know him by demeanor first are surprised by his trade. He has a certain zest for life, enjoys drinking and is often smoking; both habits he will aggressively offer to share with those around him. He is vaguely benevolent, and fairly generous, his simple tastes making greed useless to him.
Bio: Rolf comes from a long line of necromancers in his mountain hamlet of Estercrest. His family has had a great deal of Mana in it for as long as anyone can trace back, and somewhere along that family tree they turned it toward death. Their trade makes some people uneasy, but the people of Estercrest have long since embraced their usefulness, even if they keep their distance socially. The White family have historically used their powers to settle inheritance disputes, find lost things, or even solve murders by simply asking the dead about it.
They are also a force of protection for the village, undead creatures fear to go there, and the White family will even travel when asked by a foreign community.
Rolf is the eldest of three siblings, one shows no gift, and the other is their father's current apprentice. Rolf was the apprentice when he was younger, traveling with his father and learning the art. But he is a fully fledged necromancer in his own right now, and has taken up some of the responsibility, his sister taking his place as apprentice. While his sister is training, she serves Estercrest and the surrounding area with their father. Rolf, meanwhile, takes care of any work that requires travel. His work takes him all over the country, from the most urban of cities to the most remote of villages. He makes good money, and sends much of it home to Estercrest.
Marv cursed as Orran left earshot. It looked like he was going to be doing some bitch work any way he sliced it; he wasn't about to disobey a Magus. Still, he supposed, he would rather do this than Crowley's job.
~~~
The day came and went, and into the next the victim still had not awoken. She lay in a hospital bed, having been given blood, the doctors were just hoping that she had escaped brain damage. But she had been discovered quickly, and the odds were on her side. The waiting game came to an end as the sun began to set. It started as a quiet moan, but soon she was crying out in confusion. There was no pain, the mercury had sealed her wounds up neatly.
An Automata corps officer, posted as a guard in case the assailant came back for her, poked his head in, but said nothing. He pulled a messenger sphere from his pocket and recorded a note for Crowley, sending it off.
Meanwhile, back in the room, the confused cries first died down, then turned to sobs as she felt over her missing arm.