For clarity, what I meant by 'so that the BTS can be off the table' was so that it can be off the table at the end of turns 1 and 2, thus giving it immunity to the enemy's attempt to counter-attack it, which I think is a big advantage for a BTS.
From turn 3 onwards it would have to remain on the table or give a point away as if it was destroyed.



Destroyers are good, but I think it depends on how the army is being played. I see Necrons as a fire fight orientated assault army, so there is only a minimal requirement for long range shooting or the sort of conventional firepower that destroyers (especially heavy destroyers) deal out. Since I am looking at army builds that leave very little on the table I am evaluating units based on their Fire Fight and resilience above anything else.

Assessing Destroyers
Space Marine Devastators are accepted as being good at Fire Fights for their cost. Therefore anything that is as good or better for the same good can also be classed as good at Fire Fights, so I will use Devastators as a base line for comparison.

Devastators (Codex Astartes) and Destroyers (Necron) both cost 62.5 pts. They both hit in Fire Fights on a 3+, giving you 0.66 hits per unit or one hit per 94.7 points you spent on the unit.
It takes two standard hits to wound either, meaning two hits on the unit costs you a 62.5 model and a single hit on the unit costs you 31.3 points. They both die instantly to Macro and Tk, so either of those types of hit costs you your 62.5 point unit. Therefore Devastators and Destroyers are both the same in a firefight, and this means (as Moscovian said) Destroyers are good.



In addition, Destroyers are skimmers (can't be caught in Close Combat), Mounted (count as vehicles in terrain; a negative), Necron (can regenerate), and have an increased movement speed meaning an increase assault range. Therefore Destroyers are better than Devastators in Fire Fights.

However, if you intend to assault from a Monolith and not have models on the table, Warriors and Immortals are better per point spent than Destroyers in every way except the Skimmer rule (which isn't that big a deal since you get a lot of control over combat placement due to monoliths) and the 25cm range (which is a very useful increase).

Warriors cost 33 per unit, have a Fire Fight of 4+, so you get 1 hit for every 66 points spent. They take two hits to wound as with Destroyers, but those wounds cost you only 33 points or 16.5 pts per hit taken. Warriors give more bang for your buck in Fire Fight than Destroyers or Devastators, making them very good in Fire Fight.

Immortals cost 40pts per unit, and have a Fire Fight of 3+, so you get 1 hit for every 60.6 points spent. They die as easily as Warriors and Destroyers, but the wounds cost you 40pts each. This make them the most efficient use of points in Fire Fight of the units compared (and the most efficient fire fight in the Necron codex, which would require a larger table to display ).

As a side note, since Immortals are slightly better at FF than Warriors per point spent, but cost more per unit and die as easily, Warriors should be placed to become the first casualties.

If anyone is interested in how the whole of the Necron army breaks down on when assessed for assault and firefights let me know and I'll post the rest of sheet I whipped up. I think it highlights some interesting comparisons, but then I've always liked optimising armies

you dont get to choose if you phase out or not. every broken necron unit that isnt an engine, phases out. protecting them from reprisals in turns 1 and 2 is much less important than on turn 3 (since they can just heal themselves anyway) and again, come turn 3, they will break, and you'll be BTSless when it counts.
so a BTS infantry unit just needs to be shot at once or twice to break and count as destroyed. it's too easy to achieve.
all necron infantry should wherever possible be positioned to consolidate into a fresh monolith and off the table (which is another reason why you should try to have formations of two monoliths or more) but you should assume they're going to count as destroyed at the end of the game (because they'll either be left off the table and count as destroyed, or left on the table and then destroyed for real if not just broken to count as destroyed)


as to destroyers, the problem is not the unit itself, which is fairly priced and reasonably useful, but rather, its place in the list.
its a small size infantry unit which will probably be the BTS, whose inclusion forces you to leave behind more efficient or useful units (basic infantry and portals respectively) and more troublingly, requires taking a very expensive BTS, or accept that you're going to be playing 1 objective down. they quite simply dont work well within the way the necron army is built to play, while compounding the problem by making you take other sub-optimal units to compensate.

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~Every Tool Is A Weapon, If You Hold It Right~

True - if a formation 4 could be bought for 250pts (62.5x4=250) instead of 6 for 375pts (62.5x6=375) it would probably avoid this issue with Destroyers being a likely BTS. But they can't, so them's the breaks.



I know, but you do get to choose where you put them in turn 3, so could potentially keep them out of harm's way to claim objectives, fight an easy enemy or simply not come out of a portal until your last activation. I was considering 'Necron Lord, 6 Warriors, Pariahs, 3 Immortals' as a 10 unit BTS (405pts), so I'll take your advice to mean that you think it is difficult to keep them from breaking on turn 3, rather than impossible.

That being the case, legitimate BTS options are probably a Harvester (so expensive it means building the entire list around it), a Warbarque, or a larger Monolith formation.

Warbarque Supreme Commander 350pts - Takes 12 hits or 6 MW/TK hits to kill.
Maxed out 3 Monolith Phalanx + 3 Obelisks 425pts - Takes 20 hits or 10 MW hits or 9 TK hits to kill.

SURVIVABILITY
The Monolith formation takes more hits to kill. The Warbarque costs 75pts less, but can only take 60% of the damage before being destroyed.
The Warbarque can't be phased out (which is extremely important for a BTS).
FIREFIGHT DAMAGE OUTPUT
The Monolith Phalanx has 12 FF attacks on a 5+ = average 4 hits (1 hit per 106 points spent)
The Warbarque has 5 FF attacks on a 4+ = average 2.4 hits (1 hit per 140 points spent)
UTILITY
The Monolith formation has 3 portals. It can spread over a larger area to claim objectives.
The Warbarque has one portal, and includes the cost of a Supreme Commander that one is likely to want anyway. It is slightly faster at 20cm per turn.

JT, have you do you considered a Monolith Phalanx instead of a Warbarque?

there's something to be said for both options. in a number of ways i find the warbarque to be less useful. because the monoliths have a better shooting capacity and three portals are much better than one. supreme commander on a 1+ assault army isnt an absolute must (especially when you're attacking with fresh units from portals) but towards the later parts of the game when the BMs have built up a bit, you're definitely going to want all your activations to succeed. its a tough call, but in the end, i came out in favour of the warbarque for the simple fact that phase out is a massive disadvantage on a BTS, even one that takes a lot to break.

i find obelisks die too easily. without living metal, and only a 5+ RA, they're going to rely on hiding behind the monoliths, but even still, if the opponent is smart, most lists have ways to kill an obelisk or two before the third turn, if the formation is whittled down to say, 3 monoliths and an obelisk, all it takes is one decent airstrike and something shooting at them, to break the formation, at which point you've lost the BTS. at worst, it takes 6 formations shooting ineffectually to cause it to break, twice as many as the warbarque, yes, but since the warbarque doesnt care much, it wins out quite handily here.

the added cost on the monolith formation does allow you to take bigger infantry squads, but i've found the basic set with pariahs and an immortal stand is usually enough to break most formations in the game (though i havent had to come against big IG blobs yet) but it is also another 75 points
(which is an extra monolith, except with the warbarque, its an extra monolith somewhere else, not an extra activation, but that lets you spread your portals even further should you need to)

in the end, with the monolith phalanx you're gambling that come turn 3 you'll have beaten your opponent handily enough not to worry about their reprisals or losing a goal, that they've not been able to hit you solidly enough that you need a supreme commander, and that you have hit them hard enough that they cant just phase out your other units and leave all your other goals vulnerable instead.

oh, and the listbossdude has said we can test destroyers at 4 for 250 (with the ability to upgrade at 50pts each i think, dun remember) but at that point they're awful fragile for a 250 point non-core unit.

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~Every Tool Is A Weapon, If You Hold It Right~

Interesting topic. I got a test game in with the Necrons over last weekend and played with a formation of 6 Heavy Destroyers as my BTS at 300pts. They were great at hunting Warhounds and still able to run for cover through portals. I'd then spend a turn marshalling them to get their numbers back up.

Fair point. I'll probably try both.



That's exactly what I'd hope to work towards
I'm very optimistic for someone planning to use an army that is effectively all dead before the game even starts lol.



That's interesting; being able to take them in smaller formations would make them a lot more appealing.

At 250pts for 4 they are priced identically with 4 Space Marine devastators, who have identical 4+ 5+ 3+ statlines as I posted above. With Destroyers being faster, capable of regenerating and skimmer rules I'd feel churlish complaining about their fragility .

not really, since devs also get rhinoes and ATSKNF which means it takes 12 BMs to break them, not 4, they're better in assault (for ignoring the first BM is way bigger than skimmer, especially in small sized units) and when they break, devs are twice as resilient to blastmarker attrition

but yes, being able to buy them in smaller cheaper bundles goes a long way towards moving them from "never take" to "quite ok"

the problem is still that as a non-core unit that performs the core units job less effectively, i'm giving up portals to take a unit that doesnt rely on portals as much but still uses them a lot, but does nothing to reduce my armies reliance on portals...

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~Every Tool Is A Weapon, If You Hold It Right~

This is a simplified matrix of the Necrons designed to show the comparative ability of units for a specific purpose: Fire Fights. This is admittedly a narrow way of looking at any codex, but I see Necrons as a primarily Fire Fight orientated assault army, so it's a good place to start.

The columns at the right hand side show
[] How good is the unit in a Fire Fight per point spent on it,
EG if Warriors cost 33 points per stand and hit half the time (FF 4+), then you get one hit on the enemy per 66 points spent
[] How survivable is the unit per point spent vs various types of attack
EG if Warriors cost 33 points per stand and take 2 hits to kill, then the cost of each hit is displayed as 16.5



Yellow is great, Orange is good.

Some observations

Infantry
Immortals are slightly better at FF than Warriors per point spent, but cost more per unit and die as easily. If taken together, ensure that Warriors are the first casualties.
Pariahs cost almost double a warrior, and are only slightly better in FF. They are considerably better in CC. They should be taken as the only non C'tan with an Inspiring rule, which means players should ensure they are placed to be late casulaties, even if this means missing out on their CC ability.
Destroyers do not compare well in FF to any other infantry, costing more per hit on the enemy and dying faster per point spent. There inclusion should be due to higher speed (larger assault range) or for their conventional shooting (which is not ideal for all army types)


Obelisks
Obelisks have a longer ranged weapon (45) and cost slightly less that a monolith per wound received against conventional weapons: They cost 50, and require 2.66 hits to wound, so cost 18.8 per wound vs 21.5 for a monolith, or 37.6 vs 43 for a monolith against Macroweapons
Monoliths hit more in FF per point spent than obelisks; they do 1 hit per 86 points rather than 1 per 151 points. They are also twice as resilent to Titan Killing weapons.
Obelisks are essentially just ablative wounds at a lower price, and the price is not very much lower when factoring in their decreased survivability at 5 instead of 4+.

Monoliths
Monoliths are the 4th highest FF damage per point spent in the necron army (only Warriors, Immortals, Tomb Spiders do the same amount of FF hits for less points spent).
Monoliths are around 4th best at soaking up hits per point spent in the necron army (only warriors, immortals, flayed and Obelisks can take as many hits for less points spent after considering it takes average 4 standard hits on a Monolith to kill it).
Monoliths are around 4th best at soaking up Macro hits per point spent in the necron army (only warriors, immortals, flayed and Obelisks can take as many hits for less points spent; they get no save at all but are lower in cost).
Monoliths are good in Firefights, and have a low cost per hit received as well as the teleport and portal rules. They are simply great all-rounders.