Advantages - Tyranids
Nidzilla is a Tyranid list based on lots of T6 wounds and plenty of Monstrous Creatures supported by little critters - the point is to overwhelm the opponent's ability to deal with so many high toughness wounds and eventually get beaten down in combat by the big critters and a sea of little gribblies.
MCs for a combat army without mass high strength, armor ignoring attacks are hard to deal with. DoA based Blood Angels rarely have such with some of the best platforms hard to fit into such lists (i.e. Furioso Dreads, TH/SS Terminators, etc.). DoA being an aggressive army gives these MCs a serious leg up - their opponent is closing in on them, too. Most DoA lists have some sort of fire support (see below) which is going to decrease the effectiveness of the MCs - there are also 3++ and armor ignoring weapons (PFists, LClaws, PWeapons, etc.) out there so it's not a one-sided affair but DoA armies will have a hard time dealing with four or five MCs in combat, particularly if they aren't wounded before. What's important about having lots of MCs or any units carrying boneswords is you're bypassing essentially the entire defensive statline of your basic Blood Angel - wounding on 2's, no armor save and no FNP. They pay for this and these Tyranids don't really give a damn.
Anti-infantry is both a hit and a miss. When it's in range, it can be super effective and pile up the wounds to force some saves through T4/3+/FNP but that defense protects the Blood Angels quite a bit (imagine 40 jumping terminators coming for you). The (further) issue? Unless you kill what you are shooting at, some part of the Tyranid army will be engaged in combat next turn. The anti-tank facets of the Tyranid army are also pretty effective as anti-infantry against Blood Angels as well - its not their primary role but the ability to deny either the 3+ or FNP save on the Marines makes them a bit easier to drop and gives the Tyranid army a little bit better efficiency.
Bubble-wraps are a key component of the T6'R'Us list - it stops a lot of units punching through to the more valuable units further back. Without tanks or significant ranged firepower, DoA lists will have a hard time breaking bubble-wraps outside of combat and this can help negate the mobility advantage DoA lists will have IF the Tyranid player can maintain their wrap (i.e. Tervigons). The wrap itself is also fair efficient at causing damage against the Blood Angels in combat - they wont kill a lot of Marines when FNP is happening but with poisoned attacks the little guys can do those couple of extra wounds.
Which brings us to the medium guys - Raveners, Warriors and we'll chuck Genestealers in as well. These guys don't have the usual issues of being quickly shot off the table - even if the DoA list brings fire support, the MCs are a much bigger target & threat (and against Genestealers, there isn't a lot of ranged anti-infantry firepower coming their way). This means they will generally be able to support in combat and although both aren't super durable to mass ASM (lots of attacks + PFists will make short work on T4/W3 and T4/W1 with 4+ or 5+ saves), they have lots of attacks with rending (or boneswords) which can really help the MCs out in terms of reliably inflicting death to T4/3+/FNP. The speed of the Genestealers and Raveners is also important in an army of slower moving units - this allows them to bring the fight to the Blood Angels or access their support units away from the main army.
Advantages - Blood Angels
One thing which must first be understood here, a DoA list should NOT always be deep-striking and CAN have non-DoA elements (i.e. Land Speeders, Attack Bikes, Devastators, etc.). The core of the army however is units with Jump Packs which can DoA if needed - Assault Marines, Death Company, Sanguinary Guard, Honor Guard, Vanguard Veterans, etc.
DoA as a general rule of thumb isn't nearly as useful against Tyranids as other opponents - there's not that much you can get out of deep-striking right next to a combat oriented army without vehicles when you're armed with bolt pistols and meltaguns for the most part. Even dropping in flamers isn't a huge boon due to their short-range and requirement for precise placing. Vanguard Veterans however are an excellent choice to do this since they can assault on the drop and engage the bubble-wrap Tyranids look to employ (or smack around an exposed MC on the charge). This also works out well for the Blood Angels as the long ranged firepower of Tyranids is generally lacking so their T4/3+/FNP defensive statline isn't put under too much early pressure and isn't going to be rolling tons of saves until the armies start to get closer (where DoA lists work well). This means by Turn 2 the DoA army should be within range of the Tyranid army anyway but with the ability to assault that turn if appropriate.
Mobility is obviously something DoA armies have in spades. Not only the ability to deep-strike certain units but the majority of their army has a 12" jump move. Against a Tyranid army based upon plodding up midfield this gives the DoA player greater ability to control where and when they get to fight. Add to this the durability of the army against the majority of the Tyranid army (i.e. not MCs, S8+ firepower, boneswords, etc.) and the Blood Angels can really work at overcoming their serious combat lethargy against the Tyranid MCs. Not only are Tyranids slow but they cannot bull through things. Their own bubble-wrap can work against them if you tie it up and don't leave spaces for their larger bases to get through. Blocking infantry and MCs is a lot easier than blocking with tanks and with a greater movement range and the ability to move over intervening models, this is a serious advantage in the DoA camp.
This works well in conjunction with the number of meltaguns DoA lists bring - they can alpha-strike MCs. With a 24" threat range they are very capable of coming from well outside an MC's effective threat range to smack them around - the issue of course is bringing enough to bear to drop a six-wound MC (BS4 requires 10-11 meltaguns without cover, 14-15 with 5+ cover and ~20 with 4+ cover) and you'll be in range of being charged next turn. The best way to utilise this ability is to therefore ensure you bring enough meltaguns to bear on a single MC to kill it - this is where mobility and fire support comes into play. Do this at maximum distance with one unit to absorb the charge otherwise make sure you're within charge range yourself and can get to the target you are shooting at. The worst case scenario for DoA here is to shoot at max range, not kill their target and then get assaulted on all fronts - ensure this doesn't happen by positioning correctly or following up with a charge.
When fire support is brought, and it really should be, the playing field is levelled a lot more. Not only can bubble-wrap be potentially shot down at range but the DoA army isn't relying on combat and meltaguns only to drop MCs. These are still their primary methods as you want your fire support to be as cheap as chips but alpha-striking or combating a half wound MC is a lot easier than a full wound one.
The Result? & Overall Thoughts
The closeness of this battle all hinges on what support the DoA list brings. The core of 30-40 ASM is pretty decent at dealing with anything but mass MCs - what Nidzilla obviously brings in spades. That's not to say they cannot deal with them - if they can get meltagun alpha-strikes off combined with lots of I5/S5 attacks, well MCs will fall but taking on fully healthy MCs is a tough proposition for a single ASM squad. If the support provides ranged punch which can weaken the MCs before combat is engaged (i.e. Land Speeders, Storm Ravens, Devastators, etc.), the core of the army has a much easier time as they don't have to do everything and the game becomes a lot more balanced between the two factions. That being said, even without such fire support options but rather improved melee options (i.e. Honor Guard, Death Company, Sanguinary Guard or Vanguard Veterans), there are still plenty of ways the DoA list can take down take down MCs - it's all about using their plethora of meltaguns, speed and impact on the initial charge to do their advantage.
Tyranids can sit pretty in the knowledge they aren't being bombarded by 20+ high strenght/low AP shots, massive amounts of ranged anti-infantry firepower nor have 10+ tanks running around and through their lines. Hell, without all of that it sounds like they'd have a very easy time of it! However, outside their MCs or anything with a bonesword, T4/3+/FNP statlines can be hard to break and they don't have a lot of firepower to throw out which ignores this (just their anti-tank stopping FNP) or which can weaken the units from very far away (most of their anti-infantry is within the 18" range). This forces both armies into combat
Both armies are aggressive. Both armies do better in combat than not. Both armies have strengths which match-up with opposing weaknesses and this ultimately puts the outcome of the battle on who does this better - i.e. it's up to player skill. If the Tyranid players can keep their MCs out of combat except on their terms and ensure the DoA player isn't running circles around them with superior movement, they will have an easier time. If the DoA player is able to significantly out-manoeuvre the Tyranid player to ensure combat is on their terms and can use any supporting firepower they may have to weaken the biggest threat to them in CC (the MCs), they'll have an easier time. This is the sign of a good match-up and it certainly is a lot closer when the DoA has some sort of fire support but it's still relatively close otherwise.
One key point - which ever army can control midfield will see themselves forcing decisions on the opponent. If the Tyranid army sits on objectives for example, the Blood Angel's mobility is a moot point by Turn 5 - they have to remove the Tyranid models from that point. If Blood Angels control midfield though, they can literally lock the Tyranids into place and keep them away form certain parts of the board, etc.
Here is a great example of pure DoA list vs T6'R'Us btw.
