Out of curiousity and the value of seeing other perspectives, what sort of challenges do you fine folk pose to your players who have reached high ranks?

My own Calixis/Koronus campaign has the killteam into rank six and with a combination of skill and tight coordination they've consistently come out on top, albeit missing the odd limb. They've fought Slaugth, Hrud, Orks, Chaos Space Marines and a great deal of heretics.

I'm not stuck for ideas and I've a number of Haarlock Legacy adventures to gleefully adapt to their power level but I do wonder what other GMs do.

Most of the really high-powered adversaries presented so far a Chaos-based (daemon lords and whatnot). There are not a whole lot of mega-powered xeno options. 'Nids have bio-titans, which I hope FFG stats up at some point in the future; but Tau, while starting out strong, top out after a while…

The upcoming supplement The Outer Reach will feature Necrons (and possibly some other new menaces as well…?), which might be appropriate for high-Rank Killteams.

I'm developing an ork-based series of missions for my (currently low-Rank) campaign, which will culminate in a run-in with some Stompers- but I doubt those will challenge Marines above the mid-Ranks…

One of the Missions I ran had the Kill-Team unexpectedly aiding the Tau.

The Tau had a scientific research vessel orbiting one of the few agri-worlds of the Reach. They were studying various flora and fauna of the Reach, cataloging hardy strains for transplant to Tau-controlled worlds. Among the many cryo-stored samples were some of the Tyranid spores that accelerate plant growth…the idea being that hardy food bearing plants could be genetically spliced with the spores to produce larger quantities of food in a shorter period of time. There was an accident aboard the science vessel and it crashed to the planet, sinking deep into one of its seas. In the crash, many samples were released through container damage, including the Tyranid spores. In the immediate area of the crash site, kelp and krill were altered by the spores; the kelp grew prolifically and began to cover large swaths of the sea's surface, and the krill began to multiply to frighteningly massive numbers. Whale-like creatures that fed on the krill migrated to this area of the sea and began to gorge themselves on the seemingly unending supply of krill food, and were in turn mutated.

The Tau sent emissaries to the planet to smooth over relations with the planetary regent, and were soon on their way to incorporating the planet into their empire, when the Kill-Team arrived in response to Imperial Navy assets alerting them to increased Tau fleet operations in the area. The Tau were busy trying to recover and salvage what they could from their crashed science vessel, and treating with the planetary regent on equal footing. The Kill-Team's arrival to the planetary mansion was a surprise for them. The drive up the main approach was bounded on both sides by an immense orchard, and the Kill-Team could see strange "things" flitting through the branches and trunks, but no one got a good enough look to identify them. The regent met the KT in the back lawns, dressed in a bathrobe, shotgun in hand and shooting *****, while a Tau Commander in a Crisis Suit stood by and watched. As the KT were preparing to "take care of" the Tau Commander, swarms of Gun Drones arrived from the orchards…and the Kill-Team stood down until they could figure out what exactly was going on.

The Tau really had no interest in the planet, other than it's flora and fauna, and were willing to leave if the Imperium would let them gather what they could from the crash. The Kill-Team opted to help the Tau in their recovery operations, expediting their exit of the system.

On the open seas, aboard a Tau research vessel, the KT acted as overseers to the recovery operation. They were aware they were being scrutinized by Tau Water Caste researchers…and closely watched by hidden Stealth Suits. As the last of the salvage was being brought to the surface, one of the mutated "whales" attacked the floating research ship. I essentially ran the encounter as if they were combating a water-dwelling void drake. Massive bio-lightning attacks that ripped hull plating from the ship, fried Stealth Suits, and created a dangerous environment in which the KT had to fight for their lives.

Huge bio-lightning squelching Tyranid whales hoisting themselves aboard the science ship, attempting to capsize it and devour its occupants. The deep, deep sea surrounding you as far as the eye can see, filled with a morass of horribly tangled kelp (and billions upon billions of biting krill). A sinking ship occupied by opportunistic backstabbing Tau Stealth Suits. It was like Titanic meets Moby **** meets Alien. Water and bio-lightning spell disaster for someone unfortunate enough to be caught in the mix. Good times. I think I stripped two Fate Points with that Mission.

Using some of the Eldar adversaries from Rogue Trader supplements could prove rather tricky. Eldar can out-dodge, out-parry, out-stealth, out-notice, out-psychic… in fact other than not being all that physically tough Eldar can outperform most Marines. Hordes of guardians and then units of Aspect warriors with vehicle support. Should prove an elite challenge indeed.

You can also send the Kill Team to worlds with hazardous environments that don't kill them but imposes penalties. Some ideas:

• Smog world - Reduces visible ranges by 25%, 50% or 75%, and imposes a -10 penalty to BS and Per tests.
• Psych world - Triggers psychic phenomenae on any Skill test that rolls a double.
• Grav world - It's gravity, innit!
• Mud world - Most of the surface is covered in hip-deep mud: -20 to WS and Ag tests!
• Plague world - Airborne bacteria and viral agents assault the Battle Brother's physque: -10 to S and T while their suit seals are broken!
• Acid world - Corrosive atmosphere imposes a -2 penalty to their AP.
• Electric world - static electricity foils the Battle Brother's advanced equipment. Lose many of the benefits of their Power Armour, e.g. the Strength bonus, vox, improved sight/hearing and so on.

-K