Resilience
The "Wizard's Constitution" as it is sometimes known is not at all specific to wizards. All practitioners enjoy this benefit; typically, its intensity correlates with degree of magical talent.
The leading theory (at least of wizards) is that, as Magic is powered by a global, permeating energy field created and sustained by living things (again, per their theory), the presence of concentrated magical energy in a practitioner's body naturally empowers their existing regenerative systems to function at extraordinary capacity. Few practitioners disagree with this basic premise, but other traditions vary on the moral implications of Resilience, or on which exact factors correlate most strongly with regeneration. In particular, witches note that practitioners of the Dark Arts (across all disciplines) seem to be less likely to avoid the withering effects of age (indeed, some who go particularly overboard age and wither prematurely), yet their lifespans are not affected, hinting at a more supernatural, less biological explanation.
The practical effects:
- Practitioners age more slowly than non-gifted mortals. All effects vary with the strength of the gift, but an average wizard or witch might expect to age about 3 times more slowly than they otherwise might. Thus, many practitioners live well over 200 years, and some have lived much longer.
- For game purposes, all PCs have average longevity; there is no mechanic for measuring magical potential, as PCs can gain levels infinitely.
- Practitioners' natural healing is more rapid and effective. This is a fairly subtle effect, as the natural healing of humans is quite slow, compared to, say, the regeneration of werewolves. Still, recovering from injuries 3 times faster, or being able to regenerate damage that normally cannot regenerate, can be quite useful.