Mark of the Xenos is a collection of foes for a Deathwatch GM to throw at their players – something of a Monstrous Compendium Appendix – Jericho Reach. Contrary to what the title might make you think, the book does not only cover aliens adversaries, but also heretics within and the forces of Chaos without. Mark of the Xenos is a 142-page full-color hardcover that retails for about $40.
Each kind adversary in the book gets its own writeup of 2-4 pages. Each entry includes background information, a stat block, a few adventure seeds, and an in-character flavor snippet (and possibly other pertinent sidebars).
Tau（~22 pages) – All of the xenos are packaged in one chapter, but they are separated by the kind of foe/salient, and the Tau get the first turn. Here you’ll find the Broadwing Battlesuit, Commander Flamewing (a named NPC), Ethereals (the Tau leadership caste), Kroot (the Tau’s most prominent servitor species, who are more melee focused than the Tau themselves), Krootox, Knarloc/Great Knarloc, Kroot Hound, Tau Pathfinder (elite scouts), and Vespid Stingwings (semi-insectoid flyers).
Tyranids (~25 pages) – The Tyranids receive more giant and/or specialized baddies: the Carnifex (walking tanks), Dagon Overlord (a super Hive Tyrant, possibly unique), Gargoyle (small flyers), Lictor (high-powered lone hunters), Purestrain Genestealer, Ravener (tyrnanid warrior meats tunnel snake), Ripper Swarm, Trygon (giant tunneler), Tyranid Warrior Prime, Tyrant Guard, Venomthrope (like you’d guess, it’s pretty poisonous), and Zoanthrope (psyker). This section also includes several pages on new Tyranid weapons and psychic powers.
Orks (~5 pages) – A conglomeration more than a set of distinct entries, the Ork section is enough to have a smidge of the greenskins appear in your campaign, but is not at all intended to support a sustained anti-Ork effort (which makes sense, since the Orks are not one of the 17 or so groups of enemies faced by the Achilus Crusade). This section has entries for an Ork Boy, Kork Meganob, Ork Warboss, and the named NPC Big Mek Wurrzog.
Other Xenos (~10 pages) – Here you’ll find five unassociated alien species – Bruul Parasites (take over their host’s minds), Crotalids (warp-capable giant crocodiles), Diablodon, Lacrymole (shapeshifters), and Loxatl Mercenaries (reptilian baddies).
Radicals and Heretics (~20 pages) – This chapter presents threats from within (human heretics as well as demonic infiltrators), including several named NPCs. Entries include the generic Apostate Cardinal, Pontifex Guards (bodyguards for said apostate cardinal), Irradial Cogitator (demon computer), Samech Redemption Servitors, Slinnar War Machines (put your soul in the machine … maybe), and Spire Slayers (high-powered demons who bide their time, then wipe out entire hives), along with the named Inquisitor Thaddeus Hakk and Magos Phayzarus (HereTek who literally eats Space Marine organs to gain their power).
Chaos (~30 pages) – This chapter primarily covers the standard the standard demons and Chaos Space Marine types that will be familiar to most WH40K players, presenting a greater demon, “normal” demon, and CSM for each of the Chaos deities – Khorne (Bloodthirster, Bloodletter, Khorne Berserkers), Tzeentch (Lord of Change, Pink Horror, CSM Sorcerer), Nurgle (Great Unclean One, Plaguebearer, Plague Marine), and Slaanesh (Keeper of Secrets, Daemonette, Noise Marine). You’ll also find the named NPC Kyrus the Chantleader, the Obliterators, rules for making a possessed CSM, and about five pages of Chaos wargear and psychic powers.
Other Rules (~10 pages) – In addition to the adversary entries, Mark of the Xenos includes expanded rules for Hordes and massed battles (including turning points)
Mark of the Xenos has the usual quality editing and writing for the Deathwatch RPG. Every adversary has an illustration, but there are more black-and-white drawings than there usually would be (maybe Games Workshop has never commissions full color illustrations of Ethereals, Gargoyles, etc.?).
Mark of the Xenos is a necessary, if unexciting book. The GM of a Deathwatch campaign will surely want this to round out their rogues’ gallery. The players of a Deathwatch campaign will not (or, I suppose, should not) have any use for it. As for the reader, my guess is that most will not find it too thrilling. If you don’t know what all of these various foes are, then it’s probably pretty interesting. But if you already know what a Bloodthirster or a kroot or a carnifex is, then it might feel a bit repetitive. And I’m guessing that the sort of folks who would buy Warhammer 40,000 Roleplay books as reading material are already familiar with most of these adversaries. For those of you who aren’t, this should make for good reading material as well.