We will start off with Orikan The Diviner, Ctan, and Crypteks with overlapping powers to turn the tabletop into a battlefield of nightmarish proportions for your opponent.
Orikan the Diviner and Temporal Snares
This is one of the most interesting rules, and it can have a very dramatic effect on the game.
During the first game turn, all enemy units that move count as moving through difficult terrain. If they are actually moving through difficult terrain, then the unit can move the lowest of the d6 result of their difficult terrain test, rather than the highest.
Lets look at this from a Dawn of War type mission. We all know from the GW FAQs that if a unit cannot get onto the board, it is destroyed.
(pg 57 BRB )A result of a 1 means that the vehicle halts immediately and suffers an immobilization result, so if it was attempting to enter difficult terrain it stops just outside.
The result is that any vehicle attempting has a 1 in 6 chance of not only not making it onto the board, but of being destroyed and removed from play. For transports, say goodbye to whatever was inside.
The same could be said for large base models that roll bad on their movement dice to get onto the board.
Over-all not a bad ability and one way to take down large numbers of MSU Razorback spam lists. Get out those Dozer blades.
C'tan and Writhing Worldscape
Whilst the C'tan Shard is on the battlefield, all difficult terrain is also dangerous for the enemy. If the terrain is already dangerous, the dangerous terrain test is failed on a 1 or 2.
This is able to be combined with the Crypteks abilities (Tremorstave) below.
Please note that Temporal Snares above do not actually change the terrain into difficult, they just count as moving through it. So writhing worldscape does not stack with temporal snares.
Crypteks: Harbringers of Transmorgrification
At the start of the enemy Assault Phase, roll a D3 and nominate an enemy unit. If the nominated enemy unit attempts to assault the Cryptek, or his unit, reduce their assault move by the result of the D3 for that phase.
Knowing that we can get multiple Crypteks into a single unit with the seismic crucible makes it extremely hard to be assaulted. A huge boon for large warrior squads.
Just for naysayers, this is not a USR and should stack, unless faq'd.
Its a ranged blast weapon 36" that comes with "Quake"
All enemy units hit by a weapon with the Quake type treat open ground as difficult terrain during their next movement phase.
Not only can you slow down enemy units with both Seismic Crucible and a Tremorstave hit, but the presence of a C'tan on the table makes all difficult terrain dangerous.
Combine all this with other table top effects, like Night fighting, and the battlefield truly does become a terrifying place when facing the Necrons. FAQ possiblilities run high on some of these rules, hopefully that won't take too long.