I realize I may lose some of my non-Catholic readers, but here goes.
Catholics have consistently held that praying for the dead is a good and noble thing. Our prayers and works can help remit some of the punishment due to sin, for those detained in purgatory. Here is a vivid artistic rendering of this point:
J.R.R. Tolkien was a devout Catholic, with a deeply Catholic imagination.
When we help the dead, we may be sure that they will “have our backs” in this great spiritual warfare of our time. The assistance of the entire Communion of Saints is our “secret weapon.” The demons plaguing us will be just as shocked as these pathetic orcs were!
You can obtain a plenary indulgence when the “Rosary is recited in a church, a public oratory, a family group, a religious Community, or pious Association; a partial indulgence is granted in other circumstances.”
I’m pretty sure the public, outdoor Rosaries recited during Rosary Coast to Coast and Rosary Around the Lake are going to meet this condition!
Other conditions necessary: (quoting directly from the EWTN Experts site.)
3. To gain indulgences, whether plenary or partial, it is necessary that the faithful be in the state of grace at least at the time the indulgenced work is completed.
[N.B. Thus, one must be a Catholic in communion with the Pope, i.e. not excommunicated or in schism.]
4. A plenary indulgence can be gained only once a day. In order to obtain it, the faithful must, in addition to being in the state of grace:
—have the interior disposition of complete detachment from sin, even venial sin;
—have sacramentally confessed their sins;
—receive the Holy Eucharist (it is certainly better to receive it while participating in Holy Mass, but for the indulgence only Holy Communion is required);
—pray for the intentions of the Supreme Pontiff.
5. It is appropriate, but not necessary, that the sacramental Confession and especially Holy Communion and the prayer for the Pope’s intentions take place on the same day that the indulgenced work is performed; but it is sufficient that these sacred rites and prayers be carried out within several days (about 20) before or after the indulgenced act. Prayer for the Pope’s intentions is left to the choice of the faithful, but an “Our Father” and a “Hail Mary” are suggested. One sacramental Confession suffices for several plenary indulgences, but a separate Holy Communion and a separate prayer for the Holy Father’s intentions are required for each plenary indulgence.