Daerils are creatures mentioned in Infinity Blade: Awakening. Not much is known about them at the time, but information in the book supports the idea that the term may be referencing giant enemies specifically. They are also mentioned in Infinity Blade III in Act V's beginning cutscene.
Excerpt from Awakening
TEL's reference to daerils as QIP mutants suggests that all daerils were originally ordinary humans or animals, or are descended from humans and animals that were transformed into daeril lifeforms.