Rats

Max Experience Level 1 - 100 Level 2 - 300   The rat is the first monster any young Aisling is likely to encounter in Temuair. This is good because they are also the least dangerous. They are found in the first few levels of Mileth's Crypt.   Rats are always passive until provoked. This means that any aisling can walk amongst them without fear, unless they are naive enough to attack one when they are not prepared to fight. Rats can bite back, so watch out.   Rats are a good source of income for a young Aisling. When slain, they often leave behind small bits of rotting food lying around. While not very healthy for an Aisling, this food can be sold to Cian the Alchemist in Mileth for a tidy profit, anywhere from 30 to 250 gold pieces.

Spiders

Max Experience Level 1 - 220 Level 2 - 360 Level 3 - 1220 Level 4 - 1940   Spiders are are the second most common creature in the early levels of the crypt. They are a bit more dangerous and powerful than rats, but overall a good monster to hunt.   The majority of Spiders are passive. Ocassionally I have come across a hostile Spider, but it is rare. They are usually as safe as rats are.   Aside from magic items deeper in the crypt, the only things spiders drop are spider's eyes, or spider's silk. This is why they are good for a young Aisling to hunt. These two items go for 500 gold and 1000 gold respectively from Dar the Wizard in Mileth.

Centipedes

Max Experience Level 1 - 240 Level 2 - 460 Level 3 - 1950 Level 4 - 3250 Level 5 - 3080 Level 6 - 4460   Centipedes are the first really dangerous creatures you will come across in the crypts. They are the most powerful creatures on the first level of the crypt, and they are also hostile, so they will hunt you down without being provoked. Once you get to the fifth depth of the crypt however they become docile, overshadowed by the more powerful creatures there.   Centipedes are a bit of a toss up on whether to hunt or not. If looking for money, it can not be denied that the Centipede Gland they leave behind is worth a good 1100 gold to Dar, but it is also rare for centipedes to drop the coveted gland until much deeper in the crypt. Other times, centipedes will drop either the same moldy food rats like to leave behind, or nothing at all. Also note, the gland is something that is required as payment for many of the mundanes to teach an Aisling a skill, so it may be worth more than just money...

Bats

Max Experience Level 3 - 2660 Level 4 - 4230 Level 5 - 4850 Level 6 - 6750 Level 7 - 6440   Bats are first found on the third layer of the crypt, They are the most powerful creature of this depth, Be very wary, this is the first depth where the monsters are magical, and bats are especially fond of casting spells upon unsuspecting aislings. They are hostile, so will use spells upon you from far away, and without provocation or warning.   As for treasure, bats often drop Bat's Wings. These go for 1250 gold pieces to Dar in Mileth. The deeper you go the more often this is dropped, so bats are a good creature to hunt. The third layer is the first in which monsters will often drop magical items and weapons, so keep an eye out for them. Any such items will need to be identified before being put in the bank.

Scorpions

Max Experience Level 5 - 6240 Level 6 - 8610 Level 7 - 8500   Scorpions are first encountered on the fifth depth of the crypt. By the time you get this far you should know how to handle yourself well enough that they shouldn't pose too much of a threat, otherwise you had better learn how to run fast.   Scorpions, although rarely relative to other monsters, drop Scorpion's Stings. These are also used to purchase a few different spells, or can be sold to Dar for 5000 gold pieces.

Great Bats

Max Experience Level 7 - 11360   Great Bats first appear on the seventh depth of the crypt. They seem to have much the same mannerisms as regular bats, but are much meaner. They won't hesitate to blast you with powerful spells, so they are one to watch out for.   The treasure left behind by Great Bats is a good one. Great Bat's Wings can be sold to Dar for 7500 gold pieces.