Do you like Mind-Bullets?
Wish you could fire awesomely destructive Mind-Bullets in your games of Warhammer 40K?
Dare you try, the VORTEX GAMBLE (trademark pending)?
Here is my recipe for all you Grey Knights fans as to how to leverage your list building to ensure that the Daemonology Santic power "Vortex of Doom" a 12" range small blast D-weapon Vortex witchfire, can be reliably picked as well as used in your fun-filled games of 7th Edition Warhammer 40k, especially in the new meta of gargantuan creatures, super-heavies, tranny c'tannies, and Lords of War.
What you want to do is build a small 'sniping', potentially 'suicidal' unit that can shoot this power to take out the biggest, baddest, most points-expensive enemy unit in the game for fun, and of course to wreck havoc on your enemy's side of the battlefield.
D-weapon blast ahoy!
Step 1: Pick a Librarian.
Step 2: Upgrade your Librarian.
Obviously you also want to give him the Relic: Domina Liber Daemonica. This will give you a 4th Santic power you can roll for. Of course, we get the 'free' Primaris Power due to Psychic Focus, but as 'Banishment' is situational (good v. daemons, useless everywhere else), we'll ignore this for now. So now you have a 4/6 chance of getting Vortex of Doom.
Also this gives you the ability to reroll psychic test rolls of '1', which will assist you in the casting of a Warp Charge 3 power, what with all the dice you'll be chucking about.
Other potential upgrades include maximising your Librarian's survivability, so Cuirass of Sacrifice is a nice buy, as well as giving him a bodyguard of Terminators especially due to Brotherhood of Psykers, you can have Psychic shenanigans with things like Perils, and/or 'shooting' of the powers 'shared' amongst the unit, which can help extend the range of a Vortex of Doom getting 'shot'.
One is supposed to roll for Psychic powers before the game 'begins', so now's your chance to roll for Vortex of Doom. 4/6 ain't bad but don't despair if even with 4 rolls you don't manage to get the Vortex, there's still one last trick up the Grey Knight's sleeve.
In terms of powers, apart from Vortex you really want Sanctuary: to boost your unit's invulnerable save during the inevitable enemy's shooting phase as you become a nice, big, fat juicy target too good to not-shoot, Hammerhand: to give your Daemonhammer-wielding buddies a chance to lay a S10 smack on some wrong'uns, and Gate of Infinity to allow you to deepstrike out of combat, or perhaps even Deepstrike within Vortex-casting range!
Step 3: Warlord Traits
At this stage prior to game commencing you should now be rolling on the Warlord Traits, particularly the Grey Knights version. Make sure you're bringing your Librarian as part of the main BRB Combined Arms detachment to give yourself a re-roll on the Warlord Traits table. Here is why:
If by (a good) chance you've got Vortex of Doom, the one Warlord Trait you REALLY want is First to the Fray. With a 1/6 chance of getting this AND a re-roll, if you do get it you can thus place your Libby and Crew "Mordrak Style", so 1st turn instant deepstrike, no scatter. During your movement phase, put the group within 12" of the juiciest target on board be it a Fortification, Wraithknight, C'tan, etc, and await the Psychic phase!
I would heartily recommend people to NOT attempt this on a Landraider, as blowing it up might mean it's contents assault you later which is not ideal, but at least if you have Gate of Infinity you can get out of potentially sticky situations. That is, if you survive the combat!
IF you haven't manage to roll of Vortex at this stage, the Warlord Trait you do want is Lore Master. This gives you an additional 1no. Santic power to pick, so a potential 5/6 chance to get Vortex of Doom. Now's your last chance to roll for it, so make it count!
Step 4: Psychic Batteries
Okay, you gots your Vortex. Now what?
You want to ensure you have enough Grey Knights dudes on board with Psychic potential to contribute to your Warp Charge dice pool. So with the Libby and crew alone, that's 4no. dice. I recommend taking a further 3 Dreadknights along (so 3 more dice, and they're so competitive as to be auto-includes anyway). Anything else is a bonus.
At this stage you've got 7no. instant dice, during your psychic phase you actually WANT to roll a low enough warp charge dice score as possible. The less dice you roll, the less chance your enemy will be able to Deny the Witch your Vortex blast, nyuk nyuk.
Step 5: Fire for Fun
Now comes the difficult bit.
You need to be 12" away from your target, so there's gonna be a chance it'll scatter back on ya. Take a servo-skull from an Allied Inquisitorial Detachment, this will help reduce scatter by 1D6.
When you 'fire' this witchfire power, you want to be throwing at least 8no. dice (or 7no. minimum) to ensure you can pull off a successful Warp Charge 3 power. It's about 85% chance I think, but ALSO a corresponding 45% chance of Perils, so you have to take a risk here.
Did you remember to take that Relic: Domina Liber Daemonica? The ability to re-roll '1's for the casting of Santic powers = extremely useful at this point!
Unlike in previous editions, a failure DOES NOT result in the vortex engulfing the squad that casts it so RELAX. Also should you Perils, consult the chart, it's not so bad these days. After all, Grey Knights specialise in Santic, so no perils-ing on any doubles, just double 6's.
Undoubtedly, there is always a chance your opponent can Deny the Witch a successfully-cast Warp Charge 3 power, especially if they've got Psychic Defences e.g. Psychic Hoods, Adamantium Will, Talisman of Arthas Moloch, etc, etc, but at least you'll both have fun trying to cast and dispel a real cinematic 40k psychic power!
Step 6: Vortex Shenanigans
So once you've passed the test, you have to 'fire' it, but there's no 'roll to hit' as it's a blast weapon. Roll that scatter dice, and don't forget to deduct your Libby's BS trait (-4"), even better if your target is 12" of a servo skull just so you can clip it.
As a note: a 'Vortex' has unique USR of it's own so it's rules are like a Barrage, the 'hits'/'wounds', etc are allocated closest to the centre of the marker first, so this is added-value powerfulness if say you shot and hit an independent character bunched up amongst a retinue of bodyguards to maximise the 'hits'.
Also: as it's a D-weapon you have to roll on the Destroyer weapon chart. This is where the fun begins.
You have a 1/6 chance of doing nothing. So this is why it's preferably the Vortex hits at least more than 1 target, easier said than done (especially if placed over a large model with corresponding large base). You also have a 1/6 chance of inflicting maximum damage, this being instant 6 wounds + D6 wounds with no saves possible, not even Feel No Pain.
Any other results will be D3 damage/wounds, which is okay I guess. Hence multiple 'hits' and the interaction of barrage-style rules due to Vortex means this will pretty much kill whatever it lands on.
Lastly as the marker is considered Impassable Terrain you could always blow up a vehicle directly, and the blast marker has to be left as is within the footprint of now-ex-vehicle. The passengers will then have to deploy within the footprint, but if they cannot 'fit' because the Vortex marker is taking too much room, these models are therefore removed from play.
Orks in Transports, watch out!
Step 7: Field of Vortices
The best thing about Vortex of Doom is after you cast it, it will still remain on play and scatter around killing anything it 'lands' on (so it doesn't kill anything it 'moves' over, it merely blinks out of existence and re-appears in a random 2D6" direction even if it 'hits', as you use the small arrow on the dice).
This has potentially hilarious results, e.g. it scatters back over your dudes that cast it (no servo-skull deduction here!), but also it might rampage across your enemy's tabletop denying him areas to move onto, and/or scaring him from getting too close to the Vortex.
The vortex only ever disappears on a roll of a double on the dice, so I would say it's a good possibility that any Vortices you cast will hang around for a bit, a 1/6 chance of it winking out.
At this rate, and if your Libby is still alive after touching down from Deep Strike / Gate of Infinity, you can remain on play casting a Vortex a turn as long as you have valid targets to cast them onto, so you need to get pretty close to the enemy to do this! Alternatively, cast Gate of Infinity to get the frag outta the firing line! (Tau Jump-Shoot-Jump, eat my dust!)
Before long your enemy will be overwhelmed by all these blast markers scattering about randomly on the table. Hooray! You might find my multiple Vortex template useful at this stage...
Give it a go, all you Grey Knights players who's thrown away your armies after the 7th ed. codex release, I dare ya to play the Vortex Gamble!
Disclaimer: Casting Vortex of Doom does not guarantee you popularity, friends, benefits, nor does it auto-win you games of Warhammer 40K. But at least you'll have fun trying to do so.