The Cockatrice is a Weapon monster in Lost Kingdoms
The Cockatrice is a large rooster about the size of a regular human. They have long snake-like necks and a lizard-style tail, likely a reference to the legendary Basilisk which has a similar petrification power to a Cockatrice.
Whilst capturing a Cockatrice early on is quite tricky, they can prove to be powerful allies. A Cockatrice has a slow attack animation, though the move itself has decent range. This can make it tricky to land on fast enemies but extremely good against larger foes. It's relatively low cost makes it a good go-to weapon later in the game.
Even if you do not desire using the Cockatrice as a Weapon, capturing it can still be worthwhile as they are worth a solid 500 Gold per card. Early on this can be a boon, as when you capture a card you can keep it if you exit a level.
As an enemy, Cockatrice are rather difficult to deal with. This is especially true if you have no Decoy Action monsters or are trying to capture them. The Beak of Stone has a short range but nearly always turns Katia into a lovely marble statue. They will then follow this up with Ramming Attacks until the spell wears off. If you don't want to end up gravel- er, grovelling, take them down quickly or use a distraction monster.