Heroes of the Realms
BREAKING UP MOVEMENT: You can break up movement (e.g. PC with speed 30’ can move 10’, attack, then move another 20’).
MOVING PAST FRIENDS AND FOES: You can move through friends. You can move through hostile creature’s space only if the creature is at least two sizes larger or smaller than you (creature’s space treated as difficult terrain). Moving beyond foe’s reach provokes opportunity attack unless disengaging.
DIFFICULT TERRAIN: Traversing difficult terrain increases movement cost by 1 foot per each foot moved. If no other movement penalties apply, this halves movement speed. If other conditions apply, the effects are cumulative, e.g., crawling through difficult terrain uses 3 feet of movement per each 1 foot of distance traversed.
FALLING: Take 1d6 bludgeoning damage per 10 feet fallen, max 20d6. Land prone unless damage is avoided.
PRONE: Dropping prone is a free action. Standing from prone costs half movement speed.
MOVEMENT WHILE PRONE: Crawling costs an extra feet of speed per foot moved (1 foot movement costs 2 feet). Crawling through difficult terrain costs an additional foot of speed (1 foot movement costs 3 feet).
SQUEEZING: A creature or player can move through spaces one size class lower, but may only move up to half their speed and suffer disadvantage on attack rolls and Dexterity saves. Attacks against a squeezed entity have advantage.