| Transforms the caster into a venomous, spider-like creature. The caster becomes highly evasive and gains a poisonous bite, but gains vulnerability to poison.
While transformed, any equipped weapons and armour are melded. The caster also becomes unable to evoke wands, and casting spells becomes slightly more difficult.
This transformation grants the following:
- A venom-branded unarmed attack with base damage 5 and a to hit bonus
- A +5 bonus to dexterity
- Tiny size (improves EV)
- Immunity to webs
- Melds all equipment except jewellery
- Cannot throw weapons or use wands
- Natural AC is 2
- -10% to spell success
- Vulnerability to poison. Can be negated with a source of poison resistance, but sources do not stack.
The duration of the transformation is 8 + 2d<power> turns, capped at 60.
The Shining One doesn't mind if you cast this spell, but you will incur penance if you poison a sentient, non-evil monster. Using it against animals, undead, or demons works just fine (though the latter two are immune to poison).
This spell is quite useful for low-level Transmuters, as it is fairly easy to cast and can be made reliably castable with only 1 or 2 levels in Poison Magic. Although the base damage is low, most monsters you encounter early in the dungeon are not poison resistant. Monsters will also have a harder time hitting you because of the evasion bonuses, but be aware that when they do manage to land a hit, you'll have very low AC to reduce it. Octopode and felid transmuters won't have to worry about the AC reduction, as their natural AC is already extremely low.
Be careful about using this spell around enemies with poisonous attacks, as it is impossible to have poison resistance while in Spider Form (and you'll be vulnerable to poison unless you've found a source of rPois). For poisonous enemies, consider upgrading to Ice Form later, if your skill progression makes it worthwhile. Other hazards to watch out for are high-accuracy effects that target AC, such as Fireball or Airstrike.
Prior to 0.19, Spider Form gave a large stealth bonus.
Prior to 0.15, Spider Form provided above-average speed and the ability to cling to walls.