Well,
i was giving a same question to myself. If we ignore obvious, that one is a promo and thus not legal in tournaments and also hard to get if you are not in US, we have some aspects to judge.
When we go for manacost, Blur is a winner. You can use discounts with Enchanters ring (why a necro wear one, i dont know
). You will probably spend around 2 to 6 mana in case of ranged attacks during the game and this will depend on a game itself. Am i standing against Hurl Boulder mage or Straywood Aviary.
Spellbook cost. Both are for 2 points in case of Necro.
Type of spell - Enchantement x Equipment. - I dont met much necors using Battleforge, so i will take that both of these spells will be casted by mage itself. You spend an Quick action in both cases. Cloak takes a slot which can be used for Elemental cloak, which is only other item in a game so far we can take into this equation. Difference between enchantements and equipment lies mostly in the tools that deal with them. Will i spend Dispel on Necro. Probably yes. Will i spend Dispel while facing Necro? No, thank you. There are lot of curses he can have and which i would probably need to destory in this match.
So, my conclusion is, Blur should belong to Mind school only and if this promo will came out in a current form, Cloak is not needed.
To your qustions,
1)You will probably be able to keep some distance but at one point, you will have to face your enemy and then you will need armor. I take "Obscured" trait as a tool that gives me turn or two before i will get in range.
2) Zombies could be outsmarted (bloodthirsty) but in case of obscured, we are talking about Range attacks. Dark schoold doesnt have intercept so i think it doesnt matter what creatures Necro is using.
3) nope
4) Well, this is a theoritical field right now. If PvS will introduce some Light attacks, that will become "new acid ball" then cloak will also gain some value. Other thing is, how many non-holy mages will run light spells right now or in the future.
To close this up. Range 0-1 is not that hard to achieve in case of Necro. Druid will probably gain one more round but at the end, things get personal. Blur wins for me on all levels right now.