since I've noticed that the ways Hermetic Magic may or may not grant immortality are a recurring topic on this forum, I propose you to make a FAQ entry about it.
Moreover, I humbly propose the following material, in whatever revised form as you may deem appropriate, as stuff for the entry template:
Q: Can Hermetic Magic make a mage immortal ?
A: Current (AD 1220) canon development of Hermetic theory allows to greately minimize, but not completely overcome, the effects of aging, as shown by the effects of a longevity ritual.
However, a mage may accomplish levels of immortality well beyond that if one has, or is willing and able to develop by Mystery Initiation, the appropriate exotic magical insights as Hermetic Virtues.
Two kinds of immortality effects can be accomplished with established Mystery improvements of Hermetic Magic:
What may be termed "lesser immortality", by which the effects of aging are completely nullified, but the mage remains liable to warping, which will eventually cause him/her to be removed from the earthly plane. The advantage of this method is that up to that point, the mage remains completely human, with all the innate perks that come with human nature, such as unlimited freedom of movement, unrestricted potential to change, learn, and self-improve (which unfortunately includes the liability to be permanently diminished or destroyed by violent means), and the ability to draw power from multiple supernatural realms.
What may be termed "greater immortality", by which the mage is made immune to the effects of aging, warping, and, to a varying degree according to the method employed, permanent damage or destruction. Apparently, this is incompatible with human nature, but requires transformation in some kind of supernatural creature.
By their very nature, supernatural creatures are static and completely immune to the effects of aging and warping (they are already as "otherwordly" as they could ever be). According to the type of supernatural being, this may also grant also a varying degree of protection from lasting bodily or mental harm. However, this exacts a corresponding price in that the mage's ability to learn, better itself, and/or roam freely in the mortal realm are significantly limited without specialized magical help. Typically, there is a inverse proportional relationship between these three features, invulnerability, ability to learn without magical assistance, and ability to roam freely without magical assistance. Also, differently from humans, a true immortal can only be linked to, and draw power from, one supernatural realm ever.
So far, Hermetic researchers (i.e. mystagogues) have discovered effective methods to transform mages into humanoid faeries, magical (alchemical) humanoids, ghosts, spirits, and, by twisting the effects of Final Twilight, sentient magical beasts as well.
Various methods to accomplish these two kinds of magical immortality have been published in the following supplements: TMRE, HoH:MC, RoP:D, RoP:I, and GotF.
By evidence of the rules published in the above supplements, what the RAW (p. 79-80) tells most mages think, the Limit of Aging to be an effect of the Limit of Essential Nature, is a proven wrong theory. The Limit of Aging is a flaw of Hermetic theory and has absolutely nothing to do with the Limit of Essential Nature or the Limit of the Divine.
Also, while the Limit of Warping is correctly thought by some mages to be a manifestation of Limit of Essential Nature, there are two caveats:
While it is not possible to prevent Warping and remain human, the specific effects of Warping can be controlled, and it is a flaw of Hermetic Theory not to have such an ability.
Moreover, the Limit of Essential Nature itself does not prevent transforming a human into an immortal supernatural creature for good (alas, the reverse does not seem true), and the inability to do so is another flaw of Hermetic Theory. Such a change is within the power of magic and the essential nature of human beings. Cumulative warping does that in an uncontrolled, and therefore typically hapzard or harmful, way. Appropriate magic can do that in a controlled, and therefore typically beneficial, way. The Divine, for its own reasons, does not seem to interfere in this.