Here is a brief description on Argalas. When the word Argalas is used in this article, it is meant to be shubha-argala. Otherwise the word Virodha/ Obstructor is used.
This is a powerful technique used in jyotish to find out why the significations of a graha/bhava may not be giving/furthering up to the expectations.
Grahas in 4th, 2nd or 11th from a graha or a bhava cause Argala. While Virodhas/Obstructors will be 10th, 12th and 3rd respectively. If the Argala furthering graha is stronger than the Virodha, then the former prevails. So let us briefly understand this concept. Take a point. 4th from the point is Home/happiness-from home. The obstructor becomes 4th behind the point or 10th from the point. So 10th becomes a Virodha/obstructor to the 4th and cancels the shubha- argala/happiness caused by the 4th. 10th is work in the outer world. 4th is the happiness derived at Home or in the inner world. Now let us take 2nd from the point in question. Remember the point can be a bhava or a graha. 2nd from a point is gain in jyotish shastra. What is 2nd behind the point? It becomes losses. So 2nd is shubha-argala and and 12th from the point in question becomes a virodha argala.
More : 3 or more malefics in the 3rd from a graha/bhava in question cause vipareeta argala which can be very favorable. Sometimes 5th from a graha/bhava also causes Argala and the 9th becomes the virodha for it. For the nodes the counting is done reverse, since their natural nature is retrograde or opposing. An unobstructed Argala is very fruitful for a bhava or graha whichever the case may be. As per Parasara, the Argalas caused by one graha will give results, with two medium and more than two excellent. The effects of the Argala are given in the Dasas of the Rasi or Graha in question concerned (Vimsottari, Kalachakra etc.).
This technique can be powerfully used in Kaalachakra to find out if the Dasa of a Rasi will be favorable or not.
OM Tat Sat