Chryssalids are still part of the aliens' arsenal, and the aliens will still deploy them against resistance bases, though not quite as commonly as previously. They have however made some changes to the chryssalids that make them even more deadly. Rather than injecting an egg in to a victim and zombifying them if they kill their victim, they inject their victim with chryssalid toxin with their attacks. As well as the damage suffered from the initial attack, the toxin does heavy damage over subsequent turns unless healed, and if the victim dies for any reason while afflicted it will turn in to a chryssalid cocoon. This cocoon will spawn chryssalids in subsequent turns unless quickly destroyed, spawning up to 3 newborn chryssalids. Chryssalids born this way have low health, but can act on the turn they spawn, probably infecting others and causing the situation to get out of hand very quickly. Healing a toxin victim quickly is essential, and if no healing is available, evacuating them to the Skyranger is preferable to allowing them to die while toxified.
In addition to their new life cycle, chryssalids also have the ability to burrow. Chryssalids can be found in roaming pods as usual, but can also deploy as single units that remain burrowed most of the time. If an XCOM soldier approaches close enough they will unburrow and attack that soldier on your turn. Burrowed chryssalids will pop up occasionally, giving you a rough idea of where they are, and can be forced to surface with battle scanners, the Gremlin's Scanning Protocol, or any AoE attacks. They can move while burrowed; you will hear the gravel churning during Alien Activity. If the 'battle music' is still playing, then the chryssalid's hole is still in sight radius: you may want to have some of your squad in overwatch as you move forward, ideally leading with a Ranger with the Bladestorm ability to counter.