The surface level of the Bug Temple, called BugWil is an area that many players exploit to rapidly level their characters through several of the first experience levels. This strategy (if successful) can increase early game survivability since the PC will likely have much higher health, power points, more talents, better skills, and more class powers than a player who simply begins the game adventuring near Terinyo. Another advantage for many players is that this levelling can take only a few hundred turns, which can greatly ease the difficulty of speedruns.
The wilderness area of the Bug Temple is populated mostly be Greater claw bugs. These bugs have relatively low health and give 1200 experience each. While lethal in melee range, their low health means that they can fall to a few bolt spells, or even missiles.
As of v. 1.2.0 greater claw bugs can shrug magical bolts — making it harder for early game spellcasters to 'scum' experience using this strategy without serious risk, as low effectivity bolts may fail.
Very little preparation is necessary to survive the Bug Temple... as long as the PC's bolt spells work. Any caster with a starting bolt spell, notably Wizards , Druids , Necromancers , and particularly lucky Priests , may simply travel directly to the Bug Temple at level 1. It is not necessary to stop at Terinyo to pick up food since most characters have enough food to make the trip, but the player may if they desire. It is probably best simply to head due west and cross the river, since this minimizes the chances of running into dangerous wilderness encounters. Characters without the swimming skill will always be able to safely cross one square of water if they are at full health. If the player is lucky enough to start with torches, at least one, but preferably two, should be lit to increase sight range prior to entering the Temple.
Hurthling archers can, in principle, also attempt this. Greater claw bugs have a DV of 30, PV of 12, and about 18 Hits. In this case, archery talents should be taken to start: Good Shot, Eagle Eye and Keen Shot will give a berserking rockthrower (don't use your sling!) a to-hit of around 45, and base damage of about 28--enough to kill a greater claw bug in 1-2 successful hits. Most other archers do not have sufficiently high weapon marks to be able to pass the greater claw bug's PV and kill it before it engages them.
Any character with a sufficiently strong (preferably blessed) bolt spell wand with a couple of charges (4 is probably ideal) will be strong enough to at least kill one greater claw bug for 1200 experience.
Immediately upon arriving in the Bug Temple, the player should see a greater claw bug northwest of them. Stepping on square down will move the bug onto a line that will allow the player to bolt the bug. It is extremely important that the bug not have the opportunity to advance next to the player. With 160+ speed, the bug will move two steps every other turn, and thus may be able to approach and attack in the same turn if the player's timing is wrong. Players should make note of the turns when the Bug steps twice, and take this into account when they move. Also note that the bugs will preferentially approach from the diagonal. In some circumstances, it is possible to move in such a way so that the bug will not make any progress toward the player because they want to move to the diagonal first. Use this to your advantage. Keeping to the edges of the board for a hasty retreat is also recommended.
If your character is a caster engaged with bugs, be prepared to cast from health. Especially against the first one or two bugs, there is a strong possibility that the player will run out of PP before the bug is dead. Casting from health may reduce your Mana score slightly, but can save the player's life.
Hurthling archers or wand users engaging the bugs should always be aware of the number of charges/ammo available to them. Running out at an inopportune time is likely deadly.
With a minimal number of kills, the player can reach level 9 or so. Advancing beyond this point will become increasingly tedious since the experience required to level will start to increase dramatically, the amount of experience from the bugs will begin to decline due to diminishing returns, and, unless the player is quite patient, eventually most of the easily accessible greater claw bugs will be killed. To reach above level 12, the player will almost certainly need to risk engaging the group of killer bugs in the centre of the map--a much more dangerous proposition.