A World Without Heroes: Beyonders, Book 1

Characters called Displacers can detach and reattach body parts, so there's quite a bit of that, as well as characters whose eyes and ears were forcibly removed, though that's not described in detail. Dogs devour one character, a giant crab snips another dog in two (described), and another character is stabbed to death with a poison-tipped knife. The main character is tortured with a venomous snake and a sensory deprivation chamber. Giant frogs attack and are hacked to bits. Main characters are attacked often with swords, crossbows, and knives. Characters eat themselves to death in a palace-prison.

Puffballs in a cave make characters forget who they are. Venom from a snake is a hallucinogenic truth serum. An addictive berry makes minor characters eat and eat while they waste away and die.

Parents need to know that this fantasy novel is darker than most fantasies targeted to kids. It's also pretty long at 450+ pages. Violence isn't constant but can be jarring, with a character torn to bits by dogs, a dog split in two by a giant crab's claw, and torture of the main character with a venomous snake and a sensory deprivation chamber. The main characters are very brave and earnest, however, as they work together to try to save a world from evil. This is the first installment in a series.