Pattern Sorcery is the art of incorporating the Pattern itself in your sorcery spells. The cost is high...105 points is a lot to tie up in two combined powers, however Pattern Sorcery was never intended for beginning players, or for that matter most Elders. It represents a true level of mastery if the ways of the cosmos. Both players and GM should consider it carefully before introducing it to a campaign, because it could be easily be abused and unbalance the game... it will require a fair and firm hand to adjudicate in some cases. Why would anyone want this?
Except for the microspell that permits one to summon material from elsewhere, and the teleportation microspell, regular sorcery and even runic sorcery only work in one given shadow. By use of time consuming changes, or the still limiting but easier use of a lynchpin, each spell needs to be recalibrated one way or another for each shadow it's used in (and that includes teleportation because you still need to have the correct 'magic of shadow' lynchpin to leave from anywhere). Spell effects are usually always broken when you cross a shadow to another. For example the basic 'Turn to Stone' spell listed in the first rule book can be countered just by dragging the victim from one shadow to another.
The Logrus and perhaps Broken Pattern Tendrils are usually the only means of firing a spell off from across shadow lines. There is an important distinction to be made here.. The Logrus is still taking the spell from your point of origin, to the place you want to fire it off, and releasing it there. The spell is not crossing shadows, it's being carried by another power and released from afar.. and on top of that you still must calibrate you 'magic of shadow' lynchpin even if the Logrus does carry it. Application of another Power as a Defense (Pattern, Trump, or Logrus) enables you to counter most sorcery spells anyways. True, these defenses are not very quick to bring up, but if you can do it, they are impervious to basic sorceries.
Pattern Sorcery lets you overcome those limitations and more, that's why it's expensive.Pattern Sorcery comes with a few intrinsic benefits, along with the addition of some new micro-spells that work with the existing Sorcery system.
The lynchpin 'Magic of Shadow' becomes obsolete. Instead the Pattern itself is interwoven into the spell and that particular lynchpin is no longer necessary. What this does is basically make it so that the spell will work in any shadow, and you no longer need to use the 'magic of shadow' lynchpin to calibrate your spell for any particular shadow enviornment.. the Pattern does that for you. Don't think of it as a part of a spell you no longer cast, think of it as a part that you have already cast with the bulk of your spell. Just as Greyswandir has a part of the Pattern in it, so does your spell have a small piece of the Pattern tied up temporarily in it. For a lack of a good analogy, the Pattern becomes the active culture in the yogurt that is the spell. What is actually happening is that part of the spell is automatically adjusted by the presence of the Pattern, making it functional in any shadow, at any time. There are of course limitations. Shadows where the power of the Pattern is blocked, or shadows were magic does not function at all can still prove to be a hinderance. In the case of where the Pattern is blocked, but magic still works, the Pattern Sorceror could still use the old fashioned 'magic of shadow' lynchpin.
Shadow effects now are unaffected by different layers of shadow, by the same principal described above. To put it bluntly, dragging someone from one shadow to another doesn't instantly break the spell any longer. The spell with an element of the Pattern in it, is now considered for all intensive purposes 'real', and it moves or crosses through shadow just like you do, and remains unphased by that movement, just like you do. Note, however as above, if the spell tries to cross into shadows where Pattern is inherently weak, non existent or blocked, the spell will also be similarly affected. Pattern based sorcery is no longer lightly dismissed by other powers. Pattern Defense may take quite a while to wear away such a spell, and the GM may rule that basic Pattern Imprint may not be enough to ward off or break such a spell.. or that it may become a matter of a time consuming psychic process.. like forcing a trump contact...high psyche could be a big help in this case. Otherwise API may be necessary to shatter or shield against the spell. Spells can be defended against or broken by Trump or Logrus Defenses, but not without cost. A Trump Defense will still require a comparison of the two relative psyche's.. While use of the Logrus will work but could result in a powerful shock of feedback as described on page 44 of the ADRPG (Logrus sensitivity to Pattern). The cure may be very well worse than the symptom!
If the GM in the campaign is using sentient, or even semi-sentient Patterns, than you can rest assured that by using part of it in your spell the Pattern will know exactly what you're doing, at least in terms of the spell. You also suffer the chance that the Pattern will inact a 'line item veto' on your spell. This power does NOT confer the ability to hang spells on the Pattern (that is an advantage exclusive to the Logrus).
At the GM's discretion, you may need a new place to store your spells. While this is an optional limitation, it is not unreasonable why a special receptacle may be necessary to hang Pattern Sorcery spells. Remember, you have a piece of the Pattern stored in that spell, and a conventional 'hanging' tool may not have the capacity to handle that. A special device could be created by someone with API and conjuration...
Lastly, Pattern Based Sorcery is very eye-catching to those with extra senses. Even in their 'hung' state they will be glaringly obvious to someone with mage sight (by ability or spell), Logrus Sight, or even API. Placing psychic neutraility on a artifact used to hang Pattern sorcery spells is not sufficient to hide them, such an artifact would require four or more points to render such hung spells invisible to those who could see them. When activated, they leave a trail through shadow just like a hellrider does