Legend of Grimrock Earth Magic Spells
Poison Cloud

Required Level: Earth Magic 3

Upgrades: N/A

Evaluation: Basic spell. Quick and cheap to cast, but requires enemies occupy a single space in order to take continuous damage. Ineffective against the early-game Skeleton Warriors that make up the most difficult opposition on the first two levels.

Poison Bolt

Required Level: Earth Magic 7

Upgrades: Improved Poison Bolt (Earth Magic 27)

Evaluation: Upgrade from Poison Cloud that deals more damage and can be cast from a distance. More useful than Poison Cloud in almost all situations. Even when upgraded, still pales in comparison to other offensive spells.

Enchant Poison Arrow

Required Level: Earth Magic 11

Upgrades: N/A

Evaluation: Enchants any arrows or quarrels you place in the Mage's hands. Poison damage will often linger, making this potentially more useful than other enchantment spells.

Poison Shield

Required Level: Earth Magic 13

Upgrades: N/A

Evaluation: Provides +35 Resist Poison. Poison Resist is hard to come by on equipment. However, past Levels 3-4, poison is significantly less threatening as Antivenom potions become more readily available and poison damage is largely relegated to traps.