Is my math right?

[Benjamin]

A 5+ save is better than a 4+ save that needs to be re-rolled, correct?

I was just rolling around the idea that Null Zone could put a hurt on an Azreal-IG blob in this fashion.

The counter-point is that the 4+ re-rollable is better than the no save that would normally occur otherwise.

Just some Sunday musing as I do chores around the house.

[GossWeapon]

A 5+ is better than re-rolling a successful 4+ I think you are ok on that one.  Null zone is hurtful, but who cares, it's a guard blob with a pace marine character.

[the_trooper]

Sunday musings procrastinating you mean. 

A 5+ has a roughly 33% chance of succeeding.

A 4+ has a roughly 50% chance of succeeding.

If you force someone to reroll the successful 4+, they have a 50% of failing the successful roll which I think ends up being 25% total. (My math being 50% of 50% is 25% of the initial chance) It's totally possible I need more coffee here and I'm wrong but I think you are right.

[Benjamin]

Null zone is hurtful, but who cares, it's a guard blob with a pace marine character.

It's a thing in Plainville, a few players are running it.

[Benjamin]

Sunday musings procrastinating you mean. 

I so wish. Just trying not to be bored while spring cleaning.

[GossWeapon]

I wouldn't bother with null zone just for that unless its really heavy in the meta.  Just drown them in fire and bullets.  The unit is cool, but is it that much of a nightmare to deal with?

[Benjamin]

It's something to be dealt with.

I just think it's amusing that this blob can be nerfed back down in-game with a relatively common Librarian power. I take Null Zone all the time, primarily because things with Invulnerable saves are usually targets that need to die.

[shwnlyns]

a dark angels whirlwind is only 65 points and will put a lot of wounds into a IG blob, save half of them and you still take out a handfull of troopers.

[the_trooper]

Null zone is awesome and if I were to ever take a Librarian with my space marines, it would be the first power picked... then something from biomancy. 

[Tharcil]

I wouldn't over think the whole killing the blob thing.  If you are building a balanced list for all comers you should already have the tools you need to take out a blob.  You just need to inflict twice as many wounds as there are models in the blob.  If you are running a list that doesn't deal with lots of infantry well, you should probably start playing a 6th edition list instead of 5th.  Anything with a template is going to take these guardsmen out just fine. A platoon command squad with 4 flamers at a whopping 50 points can do most of the job quite nicely.