The Xenomorph Chrysalis.
The Xenomorph Chrysalis is a powerful, heavily armoured Scourge caste that comes as a result of scourge being used on a Prowler. Chrysalis not only are heavily armoured, but still carry strength similar to that of a Praetorian.
Chrysalis when rendered to half their hp or slightly lower will enter an invulnerable state where they give themself Chitinous Aura for roughly 30 seconds. In this state, all damage is ignored but the Chrysalis is unable to attack and is frozen in place. After this ends, it can be attacked again.
(Chrysalis in its defensive state.)
Chrysalis come as a result of using Scourge on a Prowler.
Chrysalis Stats.