Newbie mage looking for spec advice

Can you tell me why Venthyr is going to be better in 9.0.5? I am just starting my mage, and my main is NF, so i would be elated to be able to use another covenant, doing some low M+ i feel like all other mages (they are always NF) out dps me by quite a bit even at similar and lower iLVL (it may just be me though i am very rusty at mage)