As far as counterspelling to reduce/eliminate existing spells goes.
Just base it on the target, if you can hit the target w/ spells. Then you can dispel his magical effects attached to his form.
If the target is an astrally projecting mage then an assensing or projecting mage should be able to dispel.
If the target is only on the physical, then you need to be physical to dispel.
I'm pretty much against, anything astral being able to affect anything physical. It smacks far too much of the grounding out abuses. (here we have a whole army of street sams... I order a fire spirit to materialize in the middle of them, then cast a high force fireball grounding it out through the fire spirit, cooking all of them on the physical, and they can't sense me or do anything to me. If another mage shows, I can run away on astral at astral speeds.
QUOTE (tisoz @ Oct 25 2009, 12:30 PM)

I think a direct attack will work. Otherwise foci get a free pass.
I have no animus toward this position EXCEPT that all attempts to use barrier busting rules are badly broken. (they assume constructs w/ far more force, and moreso, constructs which will regenerate themselves, and attacks which only create small TEMPORARY holes in them and don't utterly destroy them! And that's for items WHICH DON"T TAKE KARMA TO BUILD/BOND and only limited connection to a physical 'anchor'). In theory, it sounds great, in practice, there's a whole can of worms that the proponents haven't addressed. See above, at best I see deactivation as the only thing an astral critter should be able to do.
Until they actually PUBLISH (and they have not in any book to date) rules for attacking foci. You cannot by RAW. (do whatever you like by house rules, but don't tell me it's RAW)
Tymeaus: there are rules for physically attacking objects to break them... we're talking about astrally... and a lot of this smacks too much of the grounding out abuses if it's allowed to go too far.
There would be no low force foci at all if they were that ludicrously easy to break. It also really bones adepts who may not be able to do anything on astral... look a force 5 weapon focus (pretty buff)... except this force 3 spirit just destroyed it by attacking it astrally and the adept may not even realize it.
See the point... the only spell which does, does not do permanent damage to the focus. It only does temporary damage which deactivates the focus until the focus's PHYSICAL FORM regenerates it's magical aspects.
Even failing that, materialized spirit w/ a sword adept in his face... how exactly does the materialized spirit attack the sword focus leaving the adept now unarmed and facing ItNW? Astral combat would be used to attack the form... adept has no ranks, the skill can't be defaulted.... you see where this is going.