Buy RS3 Cockatrice egg
The cockatrice egg is a stripy brown egg in RuneScape 3. It is small and light, weighing only 0.02 kg. Players use it to train Herblore and Summoning.
At level 40 Herblore, you can mix the egg with an unfinished spirit weed potion to make a Summoning potion. At level 43 Summoning, you can use it as the tertiary ingredient for a spirit cockatrice pouch. That pouch also needs 88 spirit shards and a green charm.
The egg drops as a tertiary drop from the cockatrice. You can also loot it from a spirit impling or its jarred version. With level 63 Summoning, you can make one from a normal chicken egg by casting Ophidian Incubation, the special attack of the spirit cobra. The spirit cockatrice can also make an egg from time to time.
Other eggs can be turned into variant eggs with the same special attack. These include the Saratrice, Zamatrice, Guthatrice, Coraxatrice, Pengatrice, and Vulatrice eggs. Each one makes its own type of spirit cockatrice, and all of them work in Summoning potions. The cockatrice egg cannot be incubated at a pet shop.