Alright, so i'm running a Dark Heresy (why else would I be here). and i'm just having a bit of trouble making things difficult for my players. Here's my players. They are all Rank 3 with 1200 spent exp.
Cleric - Knows the most about 40K out of the players, has the most wounds, toughness and armour. I can't remember his wounds but he has 4 TB and Guard Flak armour for 4 armour, so 8 damage reduction all over. He uses an Autogun and mono sword, also has some grenades and fire bombs. Assassin - Has a general understanding of the 40K setting. Stays 51m behind the other 2 with his long las when he can (So he is out of effective weapon range for most things), when indoors or close quarter situations, he duel wields auto pistols. He is also is incredibly smart in real life, so he can usually find pretty clever ways to deal with any situation. Psyker - Knows next to nothing about 40K. Las Pistol and 5 minor psychic powers, generally spasms things and then takes pot shots at things. Usually doesn't take things too seriously.
So i've run a few of my own missions and I can never seem to challenge my players in combat. When I think i've got things challenging enough they just breeze through it.
Since I didn't have time to write my own mission, I decided to run the "Edge of Darkness" campaign and modify it to up the difficulty. So far they talked to Lili, they didn't really ask much, but did learn about Evard Zed. After talking to him they went to the workers union (The assassin got in a fight with someone) and the psyker managed to dig up the information on the Narcogangs. I decided to kick the night cycle into effect, so they headed into the hostel for the night. Taking turns keeping watch, the assassin managed to notice some body snatchers eyes in the darkness, so they decided to follow them, (not knowing what they were yet) using the Psykers sense presence to guide them through the dark. They followed them to the statue on the map, there were 5 of them. When they were 15 meters away they turned on there glow lamps and threw them over to get a better look at them (I thought it was quite smart), they all passed the fear test. The Cleric threw a fire bomb (plus a frag next round) that lit all 5 of them on fire, some shots fired by the assassin and a successful spasm. It was at this point I realised how slow the body snatchers are, plus the breath leech from Psychic Phenomena meant they could only move at 2m for the first turn. Long story short, only one body snatcher got an attack in, but the cleric dodged it. Could you guys give me some ideas on how to change up "Edge of Darkness" and make my players feel the pain of Dark Heresy while still being a fair GM. I was thinking of giving the body snatchers hallucinogen grenades or make their attacks cause the hallucinogen effect.