Taboo

“People with weaknesses get killed by the people who lack them. Notice I'm not dead.”

— Sherrilyn Kenyon

A mortal creature can only get so strong, so tough, so fast or so magically attuned. There is a ceiling to any creature's ability, no matter what kind of creature it is. To break through a creature's natural limitations requires that the creature be changed it at a fundamental level. Altering oneself for power is Taboo. To break the Taboo is to do so anyways.

Most methods of breaking the Taboo are dangerous to oneself and others. Most come with signifficant side-efffects such as mutation of the body or soul, risks of killing the aspirant or driving them mad.
Still, some individuals and cultures see these risks as acceptable and venerate the act, calling it 'ascention'.

Methods

Below are listed some methods of breaking the Taboo and ascending beyond mortal limitations.

Divine Baptism:

Risk: Safe.
Side-effects: None.
Being uplifted by a deity is the most superior method of ascendancy bar none, however it is difficult to impress a god and therefore is mostly handed out to the innermost circles of the clergy or in times of great need.

Vampirism

Risk: Safe.
Side-effects: Mutation of the soul, thirst for blood, weakness to sunlight.
Becoming a Vampire is a guarantee to both surpass mortal limitations and become un-aging, though it comes with their given weaknesses and a guarantee of twisting the aspirant's personality into a dark parody of itself. If the 'gift' was bestowed by another vampire, the newly made fledgeling vampire will also be bound to their service.

Lycanthropy

Risk: Safe.
Side-effects: Bestial passenger, loss of control, weakness to silver.
Usually lycanthropy is inherited from a parent, though it can be attained through a ritual as well. Werewolves are magnificent creatures, though they have a tendency to lose themselves to their predatory instincts, especially during a full-moon.

Dragon-blood

Risk: Moderate.
Side-effects: High likelihood of physical mutations such as patches of scales, horns, vestigial wings or tails.
Bathing in and drinking dragon-blood is a possibility for those with access to it, such as Dragonslayers. It comes with a signifficant risk of death, and those who succeed often do so with physical mutations.

Demonic Pact

Risk: Safe.
Side-effects: A high likelihood of Cambion children.
Demons can make bargains with mortals that seek power. Often times paid for in blood sacrifices or other dark deeds, the more one is willing to pay the greater the reward.
The most powerful of pacts cost the aspirant their very soul.

Alchemy

Risk: Low to high, depending on purity of ingredients.
Side-effects: Likelihood of physical mutation and/or madness, depending on purity of ingredients.
Alchemical treatments to permanently enhance a person to superhuman levels exist on a sliding scale of safety versus affordability. Fully safe alchemical methods are prohibitively expensive for anybody without the wealth of a kingdom backing them.

Magic

Risk: Low to high, depending on mastery.
Side-effects: Moderate risk of madness
To transform the body with magic alone is possible, several rituals have been documented for various disciplines of magic. However these rituals are all esceedingly complex and difficult to perform, even for masters of the art. Even a single mistake is likely to lead to the violent death of the aspirant.

Star-touch

Risk: High
Side-effects: Guarantee of mutation
Star-touch is a condition usually brought about by accidental exposure to the energies of the Outside. However some mad cultists deliberately try to empower themselves by opening portals to that realm of madness. THe odds of death are high, and any survivors are twisted in body and spirit.
However, the survivors that manage to keep their minds are granted great power indeed.

Divinity

Those that have broken the taboo are able to accrue ever greater personal power. This can escalate to such an extent that the administrators take note, and indeed they may judge the person worthy to become one of them. In such rare cases they may ascend the person to godhood, either immediately or upon their death.
Alternatively they may judge them to be too dangerous and direct their followers to hunt them down.