Sirs of Deathwatch, I come to you today asking for ideas and suggestions to assist with the implementation of an idea. Basically I was reading up on the various offices of the Officio Assassinorum when I came across this delightful little idea about the Maerorus Temple from one of the story books.

The details of the scheme is that it was recognising that when taking out multiple targets of a particular threat, each subsequent target becomes more difficult to kill as the enemy realise their colleagues are dead and prepare greater defences accordingly. Therefore it would involve using dangerous and forbidden technology including human gene splicing with xenos DNA to create assassins capable of reshaping their physical form, killing their target and absorbing the biomass to trigger new mutation options within themselves to therefore make themselves stronger and harder to detect or kill.

The book went on to explain how the first and last creation of this effectively went rogue after realising she had the capability to practically topple the Imperium and it took several Grand Master members of the Officio Assassinorum, first company veteran terminators, Emperors Champions and even First Captains to cripple her and finally kill her but not before she'd wiped out several engagements out prior to this and still managed to take out most of the final squad which tried to finish her, wiping the Imperial force down to a single survivor.

I'm therefore looking for a way to implement this into a Deathwatch setting. The initial idea for how it gets them involved, don't worry about that. I'm thinking of feigning it as a genestealer cult or something less sinister and over time introducing this foe to them who is not interested in killing them outright as they have bigger plans in mind. There will also be a genuine other threat in there which keeps them on world and from what I read about it they didn't opt to glass the planet in case they managed to somehow slip away and that the kill needed to be confirmed.

The difficulty comes with creating a statline and a concept of a creature which over time will grow in strength and capability and how to represent the numerous mutation options available to them, the adaptive nature of the beast and the threat that it can present before finally an opportunity will arise for them to tackle the creature head on with whatever Imperial supportive assets they can muster,

What are peoples thoughts as to the viability?

Just roll mutations, add traits, and add characteristic bonuses every time they meet the big bad guy.

Where can I find mutations?!

Where can I find mutations?!

Core Rulebook, p.282 under "Corrupting NPCs" or Dark Heresy/Rogue Trader/Only War/Black Crusade rulebooks.

What about the Tyranid Biomorph modifications from MotX? List them and add randomly Venom Sacs and Adrenaline Glands and the like between encounters.

Looking through, I think I can now easily find ways to handle the numbers side of it. My thoughts are now more about how to handle the descriptive and narrative of a constantly changing and ever augmenting NPC...it's about how to handle how they look, how they feel and play etc

You will certainly need something - a leitmotif, if you will - to establish the continuous identity of the foe, especially if you plan to make drastic and visible changes to the physical appearance. This might range from a single catchphrase or some constant physical mark to a very detailed modus operandi.

For the first few missions, I assume you want to keep the players in the dark regarding the true nature of their foe, so you might want to think about how to initially present the beast. This could add some additional insight to her character (I'm also assuming you will initially keep him/her/it a relatively human-looking female, as in the book) - if the first few appearances are that of a spyre hunter, the group will assume she's driven by a relatively simple emotional package (boredom, killing for killing's sake, quest for perfection etc.), while if she impersonates an Inquisitor at first, the players will suspect a grand conspiracy and act accordingly.

I'd also try to send the players down a spiral of suspicion, frustration and paranoia in the first third or so - for example, the targets they're sent to assassinate or apprehend are invariably found dead by the time they get there. That makes the case personal, and also a matter of honour. The constantly changing nature of the enemy would be, in my book, a mid-campaign revelation, after the players realised it is the same NPC foiling their plans every time, and know enough to try to arrest or ambush her. That could, in turn, make the NPC feel she has a personal stake in this all, and in the middle third she could toy actively with the kill-team, while they're shocked by the continuous change, and would be forced to utilise their contacts and assets. to gear up to the great showdown.

You will certainly need something - a leitmotif, if you will - to establish the continuous identity of the foe, especially if you plan to make drastic and visible changes to the physical appearance. This might range from a single catchphrase or some constant physical mark to a very detailed modus operandi.

For the first few missions, I assume you want to keep the players in the dark regarding the true nature of their foe, so you might want to think about how to initially present the beast. This could add some additional insight to her character (I'm also assuming you will initially keep him/her/it a relatively human-looking female, as in the book) - if the first few appearances are that of a spyre hunter, the group will assume she's driven by a relatively simple emotional package (boredom, killing for killing's sake, quest for perfection etc.), while if she impersonates an Inquisitor at first, the players will suspect a grand conspiracy and act accordingly.

I'd also try to send the players down a spiral of suspicion, frustration and paranoia in the first third or so - for example, the targets they're sent to assassinate or apprehend are invariably found dead by the time they get there. That makes the case personal, and also a matter of honour. The constantly changing nature of the enemy would be, in my book, a mid-campaign revelation, after the players realised it is the same NPC foiling their plans every time, and know enough to try to arrest or ambush her. That could, in turn, make the NPC feel she has a personal stake in this all, and in the middle third she could toy actively with the kill-team, while they're shocked by the continuous change, and would be forced to utilise their contacts and assets. to gear up to the great showdown.

That, I can work with...I think I can string that together easily.

*Retreats to his GM lair of sinister evil plotting*

Glad to be of assistance. If you have any interesting developments, do share it here.