Editing Warhammer 40,000/Tactics/Imperial Agents (section)

====Fast Attack====
Fast Attack units are the scalpel of a Sisters force. Each of the units is designed to do precisely one thing and do it well. Since they do opposite things, you're going to want one of each (at least) at all but the smallest points levels.

*'''Dominions:''' Super-aggressive Sisters! They have access to Special Weapons (i.e meltas), they have Scout and their AoF gives them Ignore Cover. So let me get this straight: STR 8 AP1 Armourbane Scouts that Ignore Cover? Seriously?! If you're not giving them 4 meltaguns, punch yourself in the face right now. Eldar Serpent spam? Mmmm... delicious space elf tears. Tau suits sitting in a forest? Bend over, you're getting a lesson in MY Greater Good. Leman Russ line castled up behind an Aegis? You get my point. Give them an Immolator with Multimelta, run 18" up and melt their favorite toy. Then hop out of your ride and melt another one. 
:You could have a squad of ten in a Rhino or Repressor, but 10 Dominions, 4 meltas and a Rhino cost 210 points in total; For roughly the same cost you could get 6 dominions in an Immolator, with 4 meltas, a Veteran Superior with a combi-melta and a Simulacrum Imperialis, plus either a Storm Bolter or Dozer Blades for the Immolator. 
:These death stars are going to be priority target number one for any opponent whose head isn't firmly lodged up his own rear end, so you're going to need some soaks (Sisters who haven't been upgraded with weapons to take the Wounds for those who have). 
:Don't forget that since they can Scout they can also Outflank; if you're deploying first, take advantage of this - an opponent who knows about Dominions can easily counter-deploy his tanks somewhere safe. Outflanking plays hell with that strategy. Any other use of them is essentially a waste, as they're your only source of Melta Weapons that can reliably get close enough to make proper use of them. 
:It goes without saying that taking Flamers is a legendarily bad idea. Taking a whole pile of Storm Bolters isn't ''quite'' as thunderdumb, but again, it's an expensive way to get them and the cost is loss of a weapon that ends up ignoring both cover and armor. Don't be a bonehead. 

*'''Seraphim:''' Fuck what [[Dawn of War]] thinks, these girls are the rapists instead of the other way around. Jump pack Sisters, they have Hit & Run, their AoF gives them Shred and Angelic Visage means they reroll invulnerable saves granted from Shield of Faith. The slight rewording of Acts of Faith in Imperial Agents means that they now have Shred in the Assault Phase as well, which makes them a lot more useful. Hand flamers are now half price and Inferno Pistols are the other special weapon option, but at 30 points, half the range of real meltas, and having to get really close to use them effectively (3 inches for melta bonus, max 6 inches) makes them situational at best. 
:Inferno Pistols might still be worth it even if you don't want to hunt vehicles however, Shredding S8 AP1 is nothing to sneeze at and if you upgrade two Sisters you get four shots out of them, plus one more from the Superior's plasma pistol if you really wanted that TEQ squad/Monstrous Creature gone. 
:They can also Deep Strike, and Hand Flamers combined with AoF will be the bane of all horde armies out there as you are able to hop into position from reserves and cover them in templates with rerollable wounds. 
:Just remember, they're still T3, so if you're not taking advantage of LoS cover these girls are as good as dead. They still do some good damage to MEQ's through volume of wounds alone, moreover between their dual pistols giving them an extra attack and Hammer of Wrath they can be decent at finishing off a unit they just shot at in combat (unless it's a dedicated close combat unit, in which case you should bolt).
:Something you shouldn't rule out entirely is Hit and Run. Sure, their Initiative kinda sucks, but you're running them with St. Celestine, right? Hers most certainly does not. Most opponents will be hard-pressed to wipe more than a few Seraphim in one assault phase (Angelic Visage and Shield of Faith mean that even power weapons aren't sure-fire), so burn them, jump in and pound them, then rabbit away. Almost nothing can stand up to very much of that, and with Celestine's initiative, you almost certainly won't get swept. Just make sure to take a power weapon on your Superior to take maximum advantage of this.