Intrinsics are traits or states possessed directly by the player's character (or possibly a monster) or granted by an item. Most often these are binary in nature, meaning you either have it or you do not. There are a few exceptions. SporkHack measures resistances in percentages, as do several Angband variants. Angband allows certain resistances to combine if one is temporary and the other is "permanent" (which includes protection granted by equipment). ADOM extends this to almost all its intrinsics, making internal intrinsics cumulative with those gained through worn items.
Most common intrinsics are:
- various resistances, vulnerabilities and immunities,
- states such as being invisible, poisoned, hasted, paralyzed, deaf, or turning to stone,
- special abilities such as being able to walk on liquid bodies or to see invisible monsters.
There several ways to acquire an intrinsic. Roguelikes are famous for eating a corpse to receive qualities characteristic to the slain foe. It is known as a rule that "You are what you eat". Often there will be a percentage chance of granting one or more intrinsics from a particular type of corpse.
Another way is to cast a spell on oneself or to use consumable item. The effect of these methods is typically only temporary.
One can rely on equipment to provide desired properties. Each worn or wielded enchanted item grants its intrinsics to its wielder. Artifacts are very notable in this regard as these often provide several qualities but sometimes also have negative effects. Artifacts in some games have even been known to grant intrinsics when merely carried and not wielded/worn.
Lastly, one may risk getting mutated in the hope that advantageous genetic change will provide a needed trait.
Whether an intrinsic is temporary or permanent depends mostly on the game in question. ADOM and NetHack go with permanent changes, while in POWDER, eating corpses benefits (or penalizes) you only for a duration.