I am impressed.
The Necron Obelisk as a Super Heavy is as burly to kill as an Imperial Knight, given it's better armor and the potential of Living Metal. Its high vantage point, while making cover rather difficult to gain, gives it superb lines of sight and the actual girth of the Obelisk allows you to really force an enemy unit to have to circumnavigate quite far to get around it.
What almost everyone comments on is its very creative ability to ground gravitic types of units like Wave Serpents and Jet Bikes; or winged killers like the winged Nurgle Daemon Prince or the mighty Storm Raven. Every one of these types of units and more must take a Dangerous Terrain test when moving within 18" range of the Obelisk even when they normally wouldn't worry about such things! Over the course of the game, while it certainly is far from a guaranteed killing mechanism, it absolutely impacts enemy movement decisions and it happens on the enemy turn so it's all a bonus. That can be a lot of terrain tests. That can be a lot of suboptimal decisions made by the enemy.
Strategically
You'd prefer it to be mid field and able to blast in all directions at the enemy. It can then shift left or right, blocking enemy movement or just causing the gravitic and flying units a hell of a lot to think about as they move. It fires twenty STR 7 Tesla shots a round so it's not just taking up space! Deep striking it can put it right into the enemies way.
One issue that has caused some controversy is the orbs it fires. Clearly they are spheres and are called that, mounted on the corners. Arguments have erupted over its field if fire but for my money, its clear that they turn like a sphere and can hit anything the sphere, which has a canoptek "cats-eye" look to it, can "see". That is almost anything on the two ides it is mounted to. It isn't a perfect 90 degrees o both sides but its really close. Still be aware that someone is bound to try and argue this.
When you deploy it to start the game (going second) you might consider powering it down. This can't be done if you take the Obelisk in a Living Tomb Formation, which is worthy of note. You have to decide how you're going to want to use it before adding it to the list. In powered down mode, that pretty much completely dissuades wiser enemies from firing at it for two rounds because it gains a 3+ invulnerable save and the enemy isn't going to be likely to be close enough for you to hit them anyways round 1. It's like playing possum... Dark Evil Possum style. On the bottom of round two, you can power it up and commence termination protocols. It cannot be powered down
again once powered up. If the enemy flyers come too close in round 2 though, they might get zapped as its anti-gravity pulse effect is still active even though it cannot fire its weapons. Pretty much what it does is the same thing that happened in the Man of Steel movie where the thing lifts and then drops everything metallic!
Deep striking it precludes it from being able to just squat on an objective late in the game. I'm guessing this problem was caught in play testing. If you're playing the Emperors Will kind of a Mission, that thing could plant itself on an objective turn one and simply sit there screwing with flyers all day if you wanted it to!
Deep striking it without reserve manipulation is a potentially huge drain on productivity if it doesn't show up in turn 2, since the Obelisk is a hefty 300 points of your army. The Living Tomb formation provides an answer. The Obelisk is guaranteed to come in turn two, but MUST therefore Deepstrike and cannot power down during the game. This seems like an incredible no-brainer if your tournament allows enough Detachments/Formations. The Living Tomb guarantees it goes live and in position round two to do the maximum amount of good and the Living Tomb formation can take up to two Monoliths, though you need not actually do so. What is cool though is that those particular Monliths don't scatter if within 12" of the obelisk. Awesome.
What does it all mean? Well it means you can slingshot a gigantic amount of your army from one side of the board to the other in turn two. That's what it means! Imagine stuffing a couple large units of Infantry in the farthest corner of the board and then waiting patiently for your ride. then with reserve manipulation you bring in the Obelisk automatically and then the Monoliths (on 3+, re-rolling if you have a Comms Relay). The Living Tomb Formation allows you another ability. On the round that the Monoliths drop, each can pick up and eject an extra unit!!! Whuuuuuuuuuuuuuu! But yes! It worked wonderfully in my three test games so far. One minute I have nothing on the board and the next minute there are 30 or 40 Warriors a couple Monoliths and an Obelisk dead smack in front of the enemy. Terrifying. Now in my games there were mishaps and fun things like that to make it exciting, but once you practice a bit and get the hang of where best to deposit things etc... the fun really begins.
Now there's a few more tactical notes I'll make here.
First is, that the girth of these Monoliths is so great that you really can hide and spread out a great deal many of the Necron Infantry you're bringing in. The firepower that the Monoliths and Obelisk begin dropping is eye catching and draws the attention of the enemy and thus protects your precious cargo. This threat may perhaps even draw the enemy into unenviable charge attempts. My suggestion is to pre-measure and make sure that you are more or less going to be just close enough to allow the contents to be within 18" of a desirable target when their next turn starts so they can walk up and rapid fire. I feel this is going to take some practice to figure out where all those marks are for disembarking and landing and so on, but once you figure out the geometry, your grand entrance will be awesome.
The second thing is to lead with the Obelisk. The enemy will try to take it down and it will absorb a lot of abuse. But the real reason is that it can Thunderblitz. I have learned a deep respect for this. Smashing everything that gets in its way is fun. It also causes Fear which is fun. Obviously not everyone is affected by this but hey if you can make someone hit on a higher number in close combat? Yay! More importantly, this added attention and ill advised charges will bunch the enemy up for you. You know, with all those infantry and Monolith blasts and stuff to make them pay for it.
Thunderblitzing is also useful because it puts that exploding Obelisk nice and close to as many things as it can so if they are bold enough to charge it, well... they may pay with their lives doing it.
The Obelisk also is Tesla. That essentially makes up for any misses, with its 6's to hit becoming two additional hits. The Tesla Spheres, if you angle it right and at the right distances, it can hit with up to three turned towards an enemy/ Ouch. Its actually harder to pull off than you'd think and two spheres will be more often the case but still... it's brutal. But then it's 300 points so it ought to be right?
The Obelisk is a really fun model to play with and although Games Workshop seems to think that it should cost $160 (and I don't care who you are, that's a hell of a lot of money) it adds a great deal to the list. I'd recommend its use.
Here is the list I have been testing ideas with, and it's won all three of its games. More are to come. Note that this list can easily be converted into a 2 Detachment force for those games in which that's all that's allowed; although, lets face it, the days of that limitation are numbered I'd say given how the Codex's are written now. Also notice that the Obelisk can be added to the core of your already existing force REALLY easily and admiraly serves to update even this basic force here.
Mephrit Dynasty Resurgence Formation (Monolith heals D6 Warriors or D3 Immortals)
200
1 Monolith
130pts
10 Necron Warriors
130pts
10 Necron Warriors
85pts
5 Immortals
85pts
5 Immortals
Combined Arms Detachment
65pts
1 Cryptek
65pts
1 Cryptek
130pts
10 Necron Warriors
130pts
10 Necron Warriors
Combined Arms Detachment
115pts
1 Cryptek (Veil, Blinding Staff)
130pts
10 Necron Warriors
130pts
10Necron Warriors
104pts
8 Flayed ones
Living Tomb Formation
300
1 Obelisk
200
1 Monolith
1999 Points