Features can do various things, both passively and actively.

Nouns:
 * Self
 * Any creature
 * Single target
 * All in AOE
 * Any object
 * Any structure
 * Specific object
 * Point in space

Triggers by Noun (N):
 * Passive (always acting)
 * N takes special action / bns action / free action (granted by feature)
 * N start of turn
 * N takes damage
 * N makes check against N
 * N forces N to save
 * N rolls a d20
 * N targets N by spell
 * N attacks N
 * N hits N
 * N moves
 * N dies
 * N touches N

Conditions on some number of Nouns (N) (can be negated):
 * N has property PROPERTY
 * N is hostile to N
 * N is allied to N
 * N wishes it to be so
 * N succeeds roll by at least X
 * N fails roll by at least X
 * N is within radius of N
 * N can see N
 * N in antimagic field
 * N has completed >= X turns
 * N doesn't have full hp
 * N has >= X hp
 * Damage received by N >= X
 * Damage received by N was a critical hit
 * Damage received by N was type X
 * N is alive
 * N has condition X (given by N)
 * N and N are on same plane of existence
 * N on specific plane
 * N moved X distance straight toward N
 * N has X movement remaining
 * N made specific attack
 * N without underside exposed
 * First time N uses feature on N during turn
 * N is flying
 * N has X spell cast on it
 * N has spell with X property on it
 * N is on X terrain/surface
 * N is inside an object
 * N is in X lighting (sunlight, dim light, darkness, magical darkness)
 * N can understand at least 1 language
 * N and N share a language
 * N has >= X heads
 * N is intact
 * N has spell slots remaining
 * N had advantage
 * N had disadvantage
 * N used a weapon
 * N is surprised
 * N is bound by N (aka, N is N's master)
 * N is aware of N
 * N is in same web as N

Effects for given N:
 * Delayed effect (effect takes place after a duration)
 * Modify movement speed
 * Modify jump distance
 * Modify jump height
 * Acquire condition CONDITION
 * Ends condition CONDITION
 * Acquire/override property PROPERTY (see propertiesNotes.txt)
 * Death
 * Surprised
 * Pushed X feet in DIRECTION direction
 * Immune to feature FEATURE
 * Immune to spells with trait SPELL_TRAIT
 * Make terrain difficult
 * Disadvantage on rolls ROLL_CLASS
 * Advantage on rolls ROLL_CLASS
 * Automatic fail on rolls ROLL_CLASS
 * Automatic succeed on rolls ROLL_CLASS
 * Automatic critical hit
 * Move X distance
 * Can move through creatures/objects as difficult terrain
 * Deal X damage
 * Disable other feature
 * Know distance/direction to creature/object within X distance
 * Reduce incoming damage by X
 * Regain X hp
 * Weapon/armor corrodes
 * Ignite flammable objects
 * Expend spell slot
 * Special movement
 * Plane shift
 * Grant spell effect
 * Transparency (perpetual hidenness?)
 * Prescribed actions (randomized), any of:
   - Nothing
   - Moves in random direction
   - Attacks random creature within reach
 * Telepathic command
 * Learns creature's desires
 * Spell storing
 * Creates X diameter tunnel

Effect duration:
 * Set time (e.g., end of turn, start of next turn, end of next turn, 1 min...)
 * Repeated saves
 * Repeated saves at advantage/disadvantage with condition
 * Until action is taken to douse
 * Until certain spell is cast
 * Until other effect expires

Feature recharge:
 * Permenant
 * X/turn
 * X/lr
 * X/sr