Out of depth
For the other OOD, see orb of destruction.
Crawl tends to create many Out of Depth (OOD) monsters, who have spawned on a higher floor then where they are "usually" spawned. The source file mon-pick-data.h defines where is a monster's base floor is, so anything above that is technically OOD. The term typically refers to non-unique monsters which are much more difficult relative to where you are in the game, such as a sky beast on D:2.
Like all monsters, out of depth monsters are spawned when the floor is generated. Their 'base floor' is fuzzed, favoring the actual number, but often either up or down. However, there are also a few special cases with monster spawns which can break the "normal" rules of generation.
- Monsters can often spawn in "bands", which have their own depth. Despite orc priests naturally spawning on D:4, they can spawn on D:3 or even D:2 as a part of an orc band. (Because this is common enough, D:3 Priests often aren't considered OOD).
- Monsters can spawn in pregenerated vaults. For instance, one Lair entrance vault contains death yaks. Death yaks don't naturally spawn in the Dungeon at all, but are very tough enemies for D:8.
There are some hardcoded assurances that certain, ridiculously difficult monsters can't spawn, such as a D:2 water moccasin.
OODs are most noticeable in the Dungeon, the longest and most difficulty-variable branch, which has the most monster variety, and explored when the player doesn't have many options to deal with them. Many later branches don't have many floors, don't get much harder between floors, and many don't gate monsters by floor to begin with (harder monsters just spawn more rarely higher up). Unique monsters tend to remain challenging later on.
- Check the monsters speed and range, and determine if you can just walk away. An OOD orc priest is extremely scary, with its 17 damage Smiting that reaches the entire screen. An ogre or hydra are 10 speed melee enemies, meaning you can just run away if you see them. The same applies to the 10 speed orc priest, but only if you can keep it out of sight (where monsters can't attack).
- Use your consumables! Especially if you can't escape by simple retreating.
- If all else fails, you can simply skip the floor and descend downwards. After all, D:11 and Lair:1 are, most likely, less dangerous than a D:10 with a wandering storm dragon. Even if the floor below would be dangerous, you can at least check out what's actually in store (and decide from there).
- Prior to 0.21, monster spawning was used as a means to create out of depth monsters. If the out-of-depth timer went on too long, then it became more and more likely for these difficult monsters to spawn.
- mon-pick-data.h:1 (0.30.1)