Level 1 divination spell “waypoint”, which reveals the location of all stairs/ladders (but no other spaces) on the level. Does not work if the level is unmappable.

Monsters that hide under objects can also hide under or behind various types of terrain, such as sinks, ladders, thrones, and gravestones.

New monster behavior flag M2_CLIMB or M3_CLIMB: added to monsters that are natural climbers (spiders, ants, most Y) and with effects like being able to get out of a pit in one turn, or who can climb up ladders without having hands.