Upgraded Warriors explode on depletion of their first health bar, showering their acid blood everywhere and leaving them bisected, but still very capable, well, warriors.The praetorian's digestive and vascular systems are connected together which allows them to vomit large amounts of their acidic blood on enemies.The Alien Carrier has mantis-like claws in place of hands.The Alien Ravagers fight using enormous scythe-like claws called Hullblades, which they use to decapitate opponents.The Predator Brawlers fight exclusively using their arm-blades.Enemies infected with these spores can be seen vomiting a black substance. Bad Black Barf: When upgraded the Runner will poison enemies with symbiotic spores that turns their blood black and soupy which weakens them and allows the Hive to track them.It's best to use them as a Support Party Member and back them up with other units than solely rely on them as frontline fighters. They pack a mighty wallop with their Sinister Scythe, are great at soaking up damage, and can kill just about anything in three to four hits, but their attack speed is abysmal and not ideal in situations that pits them against multiple enemies, which is extremely common. The Alien Ravager is an extremely powerful melee unit, the most powerful in the game in fact, but they fight to kill, and since the Aliens require live hosts to impregnate Chestbursters, they're not recommended when you need to replenish your forces.
While extremely tempting, it's better to save the cap and purchase more specialized units like the Smartgunners, who can make up for the ExoSuit's firepower, or limit yourself to one ExoSuit and use it as a damage sponge to keep the enemy off your more fragile units. To put that into perspective, the Marines cap is 25 units, so almost a fifth would be taken up by just one ExoSuit. The Marine ExoSuit is built like a tank and packs some of the best firepower in the game but is obscenely slow and takes up a whopping four population points.Having the Queen lead major assaults is a valid tactic, especially once she's been upgraded with the army-buffing 'War Empress' trait. Authority Equals Asskicking: The Alien Queen is one of the the strongest units in the Alien lineup only surpassed by the Ravager in terms of attack power.The Alien Ravager, however, conspicuously subverts this - It will always kill its victims outright via decapitation, preventing later impregnation. They never recover from this state, however, so they are still considered dead for gameplay purposes. As Lethal as It Needs to Be: Despite possessing deadly claws, teeth, and blades, Alien attacks merely render their victims 'comatose' so they can be dragged back to the hive for impregnation.Artificial Stupidity: Terrible pathfinding AI, leading to units going on mile-long walks when the player's not looking, missing perfectly serviceable doors, etc.Meanwhile, the predators kidnapping Kadinsky leads to the attempted rescue mission in Marine 7. The best example is the destruction of Kadinsky's lab - the attack is part of Predator 6, and leads directly to Alien 5 after a stray plasmacaster bolt breaks the lock on a specimen containment cell. Another Side, Another Story: The three campaigns are roughly parallel to each-other, and many levels in each campaign involve dealing with the ramifications of events that occur in the other two.However, their units are fairly fragile and rely on a Queen to lay eggs and impregnate hosts with chestburster, which take time to incubate. The Aliens have the largest population of the races and typically Zerg Rush the opposition. They're reliant on a slow-moving Shrine to call down reinforcements via drop-pods, and they deploy faster than any other race. However, all Predator units can cloak and heal themselves at will by spending energy that regenerates over time. The Predators have the smallest population cap and each unit is fairly expensive. They're capable of fielding more troops than the Predators, but not as many as the Aliens and are reliant on Commtechs to call in reinforcements at designated drop zones. The Marines lack melee units, but make up for it with a wide roster of powerful ranged and utility units. Achilles' Heel: The Aliens possess a vulnerability to fire, it does extra damage to their units and negates any regenerative abilities they have.The radiation they put out stops the Xenomorph's Healing Factor. Abnormal Ammo: The marine Flame Trooper and Smartgunner can be upgraded with cobalt-60 ammo.