Its name is derived from the Serbian word for "illusion".
Although it appears to be a giant snake, the Iluzija was created from a human subject infected with the C-virus. Its mouth is filled with numerous bending fangs and it is capable of crushing an average-sized human within its coils or even swallowing one whole. The most threatening ability of the Iluzija is its ability to blend in almost perfectly with its surroundings. While doing so, the snake is nearly impossible to see, with only a mild rippling haze visible when it moves. A flaw in this ability is that the inside of its mouth becomes completely visible when it opens to prepare for an attack.
During the 2013 bioterror event in Lanshiang, the Bioterrorism Security Assessment Alliance (BSAA) was deployed into the city to eliminate Neo-Umbrella's B.O.W. forces and rescue civilians. The team led by Chris Redfield suffered heavy losses when they encountered the Iluzija creature inside an apartment complex, which greatly angered Chris who became determined to exterminate the B.O.W.
Alpha Team eventually cornered the Iluzija and manage to weaken it by attacking its vulnerable mouth. The creature fled into a flooded maze where it hardened its scales to protect itself. Unable to kill the beast with their weapons, Chris lured the monster into a pool of water and electrocuted it with power cables, finally eliminating it.