[ImmortalShade]

My gut reaction says medically induced coma would be the cats meow

[nmap]

Putting them in overlapping wards with magecuffs seems reasonable enough. Someone who can cast through two Force 5 wards would be rare.

[Companero]

I might be misremembering my fluff here, but I guess the Ute would simple have imprisoned their mages somewhere in the vicinity of Salt Lake City.

Things that can happen are MASSIVE chemical cocktails to keep them 'docile', constant sensory deprivation and being bound and gagged 24/7 to prevent spellcasting, including the use of magecuffs to prevent astral projection, and even giving them implants to kill their talent.

All of that sounds like exactly the kind of thing which would drive someone to become a blood mage after leaving prison. I feel like the imagery of that process would be great fodder for a emotionally charged game.

[Mantis]

According to the Lone Star book, mages get the chemical cocktail treatment with non-addictive psychotropic drugs to keep them barely conscious and then they bombard them with flashing lights or trideo to keep their addled little minds occupied. If they act up, they get mage masked for a few hours at a time. They also hit them with sleep deprivation so that any spell casting hammers them with drain and makes it harder to actually pull off. This is all done in holding. What happens in actual prison could be different depending on who has them.
Apparently, the only ones running actual prisons are the Federal governments of various countries. Corporations aren't allowed after Renraku tried making a game show out of basically torturing prisoners and others used them for experimentation.

[Mirikon]

Lone Star runs the prisons in Seattle, Mantis. It is the majority of what they have left in the city. And most megas have their own prisions, as well.

[Mantis]

Then that would be a change from the Lone Star source book. Probably done just so Lone Star can keep a hand in the goings on in Seattle. I found that a bit odd to read in the source book when IRL, private prisons are quite common in the US.

[Shaidar]

Putting them in overlapping wards with magecuffs seems reasonable enough. Someone who can cast through two Force 5 wards would be rare.

Multiple wards cannot cover the same volume of space, neither overlapping nor concentric (1 within another).

[Mirikon]

Wards cannot be layered or overlap in the same area of astral space. However, there are disagreements as to whether a ward is a 'field' or a 'wall'. My personal reading of things is that it acts essentially like a wall, or shell, given that, once you are past that outer wall, there is no impairment as there would be if it was some kind of suppressive field. Therefore, you can have wards within eachother, so long as they do not occupy the same area of astral space. In other words, the inner ward cannot be touching any part of the outer ward's wall. The example I would use is a ward around a research lab to keep out astral spies, and a second, heavier ward around the high security wing, to keep intruders out (or to keep awakened test subjects in). So long as the two wards do not touch in astral space, you're fine.

But as I said, there are disagreements on whether the ward is a field or wall, and it has never been made clear in the books.

[Shaidar]

The Shape of a Ward
Though wards are limited by the standard 50 cubic meters times the Magic attribute of the creator, the shape of a ward can vary and must be determined at the time of the ward’s creation. A variety of basic three-dimensional geometric shapes are possible, such as globes, domes, cubes, rectangles, trapezoids, ovoids, and more. Experiments with complex three-dimensional shapes have proven unstable, however, with the ward collapsing at the completion of the ritual. Experimental astral security designers and astral artists have had to rely on combinations of multiple simple wards to create complex astral constructions.
A ward must also extend at least one meter in every direction from the physical anchor that it is attached to (see below), which prevents ward shapes that are very tiny or very thin in any dimension.

Wards are Exclusive
Wards cannot be layered or overlap in the same area of astral space. Magicians seeking redundant astral security measures will often put a series of wards in place, much like a gauntlet an intruder would have to pass through, but they cannot place multiple wards on the same space in an effort to make intrusion exponentially more difficult. Attempting to place a new ward where it would intersect with another ward results in the new ward simply failing.

So the area is a 3 Dimensional space much like our polyhedral dice, but metahumans only interact with the hollow shell "wall" and wards have no effect on the area inside.  Which cannot share any part of their space/area with another ward.

One ward could cover the foyer of the building with another covering the R&D wing of a building and a third covering the remainder of the building.  The runners would need to pass through all three to reach the R&D wing, but each must cover a separate area of the 3D space which the building occupies.  You could even have one ward cover a few floors of a building and not others.

I've always thought of it like an egg, you can only have one shell for each egg.  Not one shell for the yoke and another for the white.  Although you can have a separate shell for each egg in the carton.

[Sichr]

Nice but OT, there is thread covering this. And discussion was fierce and endless, so lets try to avoid it here .
Back to OP: there is good Blood mage example in second Artifacts adventure book (Midnight?) except for sacrifice he is using Control Actions IIRC. Nasty.
Generaly speaking, Street Magic contains enought info. Take any magician NPC or sample char, initiate a bit and use right metamagics. Also Blood Adepts have some really nasty powers. Dont forget those