Does Shadow Embrace affect everyone or just the warlock who casted it?

• Does Shadow Embrace affect everyone or just the warlock who casted it?
  
  
  
  Shadow Embrace affects everyone. If you have 5/5 Shadow Embrace and use it on a target, it will deal 5% less damage to anyone it attacks including your tanks. Shadow Embrace does not stack, the higher ranked Shadow Embrace will overwrite any lesser ranked ones. Therefore, having multiple affliction locks with this talent is for the most part redundant. You can work this out with your fellow locks by assigning the most reliable lock in the raid to 5/5 Shadow Embrace, while the rest put only 1 point in Shadow Embrace (because it counts as an affliction effect for Soul Siphon) and the rest elsewhere.
  
  
  
  
• Is Cataclysm good for raiding?
  
  
  
  Not really. Think about it this way: with 5 points Cataclysm, you are saving 5% mana on destruction spells. Your most used destruction spell, Shadow Bolt, costs 380 mana per cast. 5% of 380 mana is 19 mana (380 * .05 = 19), so you save only 19 mana every time you cast Shadow Bolt. Divide 380 mana by 19 and you get 20. This means that you need to cast 20 Shadow Bolts to have saved enough mana for just one extra Shadow Bolt. No thanks.