Maybe I just can't find the rule in SR4, but it does not seem that you can attack someone through their foci anymore.

In our SR3 games, the big drawback to having foci around was that enemy astrally projecting mages could blast you and your team in the physical through that foci.

If that is no longer the case, is there any drawbacks to having foci other than glowing like a beacon as if to say, "I'm here, right here!" in the astral?

You actually couldn't do that in SR3 either. SR2 and SR1 both allowed active foci to act as a bridge for "grounding spells".

There is a couple of limits on active foci number and force, now, and they can still be attacked via astral space (just not grounded through) or set off wards.

"When active, a Focus has an Astral Form." (p. 191)
Objects with an Astral Form can be affected by physical damage in astral combat (p. 184)
"While astrally perceiving, a magician can cast mana spells at astral opponents. Other astral forms can engage an astrally perceiving magician in astral combat (p. 184) or cast mana spells at him as well." (p. 182)
Disrupted foci are deactivated (p. 186).

So what you're saying is, while an astral form can't ground a spell through an active focus, they can grasp it and physically bludgeon someone with it?
That is, I have to admit, a hilarious idea. But taking it off their person would cause it to deactive, right? Then again, that sounds like a pretty darn convenient way to deactivate a focus. Hmmmm, something's not right here.

Edit-Now I see where this is going.

I had a GM who fondly recalled schooling a mage with too many spell locks in SR2 by grounding fireballs through them. But then spell locks were absolutely gross!

I'm pretty sure that grounding a spell from the astral to the physical through a foci was done away with in SR3 though. A foci's magical nature can of course be disrupted by attacking it in the astral, but only while it is active, and I don't think the foci can be permenantly harmed from the astral either although I could be wrong.

Those all got posted pretty quickly!

I really don't think a projecting mage can move a physically present foci around like a weapon. Foci are only astrally present while active, and they must be in contact with their owner to be active.

As for Devil rats.... I jusst don't want to go there!

So then all you need to do, is stuff the foci inside their mage, then bludgeon people with the mage/foci combonation. Just seat it somewhere sturdy, like in the ribcage, and bludgeon away.

Keep in mind that the mage/focus/critter will eventually take damage while doing so, and be destroyed/killed at last.

Accoding to Target:Awakened Lands, Astral Constructs will support the weight of dual beings provided that they are strong enough. An astrally percieving mage could sit on a chair that only exists on the astral plane with no problem. Likewise, he could climb an astral ladder without difficulty. If he were permenantly dual natured he could even sleep in an astral bed with astral sheeps, although I suspect it would be drafty.

Purely astral things can, at least, defeat the force of gravity on a dual being. However, astral constructs are rather unique in that they act like physical objects on the astral plane. You can't stand on a ward, you'd just fall through it. This leaves the question of a astral magician beating someone to death with a devil rat open for debate. Form a game balance perspective I say no. From a funny perspective I say yes.

Devil rats aren't dual natured.

It would seem devil rats, vampires, and wendigos are the only paranormal critters that aren't dual natured. How odd. In critters, they were dual natured, and now in SR4, they suddenly aren't?

Where as you can not attack through a foci, you can attack the foci.

Sure you can dispell it but that is only a momentary inconvenience for the mage.
Note that such an inconvenience during combat can still be deadly.

The levitating invisible mage sneaking into a Coven's sanitary was none to happy when all his foci broke. Botches on stealth can be fun.

Scary thought.

Welsh Shamans with a sheep totem.

*shudder*