Plague Slime

Plague Slime can be found in Naxxramas.

Abilities
This mob becomes immune to a specific magic school depending on its color:
 * Plague Slime (Black) - Immune to Shadow spells.
 * Plague Slime (Blue) - Immune to Frost spells.
 * Plague Slime (Green) - Immune to Nature spells.
 * Plague Slime (Red) - Immune to Fire spells.