I know this, and the following, are 5th edition battle reports but hopefully it's still pertinent in terms of a learning exercise, etc. you just had to adapt it a bit within the 6th edition construct. I'll likely combine the final four battles into two posts of two each though.
The mission was an objective based mission with set objectives. Three along the table centre (lengthwise) 18" apart and two along the table centre (widthwise) in each deployment zone, 6" from the table edge. Deployment was pitched battle. Central objectives were worth one point each, objective in your DZ was worth zero to you, three to your opponent, and objective in your opponent's DZ was worth three to you, zero to opponent.
Game was against Jason Collins using Vince's Blood Angels. I won roll-off and elected to give first to Jason.
This is personally one of my favorite match-ups in 5th edition as both armies have strengths and weaknesses against each other. If both forces play well you generally end up with a very closely fought battle but if one force messes up a bit, things can slide very quickly. From Jason's perspective, he has the firepower to keep me honest and ensure my MCs aren't wide out in the open and the close combat muscle to beat the Tyranids at their own game - both MCs and little gribblies. What he lacks his mid-range anti-infantry or the ability to pour lots of firepower into squads from a distance which means my squads are more likely to get their relatively unscathed. He does have a mobility advantage though and if he can damage my MCs enough with missiles, that mobility and durability in combat is going to roll over the little guys.
So, Jason deploys relatively centrally and combat squads due to objective mission. There are 30 ASM out there plus 15 Devs, a Libby, 3 Priests and some VV in reserve waiting to pounce on any backfield mistakes. The ASM are split into double melta/PFist groups so the meltaguns can stay more mobile and drop MCs if necessary whilst the PFists engage. There is a central piece of terrain which generates good cover and potential LoS blocking for MCs so he deploys on the strong [right] side of it (i.e. where I could have easily hidden) with the majority of his firepower with one squad of Devs on the left to keep me honest.
I'm looking to get my MCs into combat with as few Fists as possible and really let the Genestealers go to work. I deploy as usual with a central grouping with Termagants covering the front lines to force the ASM to engage them or the missiles to launch frags to punch holes in the bubble-wrap. Genestealers infiltrate on the left so they are only faced with one missile grouping.
Blood Angels Turn 1
I don't try and seize. Jason moves his ASM in two groups - one centrally and one out on the right flank. The central group hugs the BLoS cover in the middle with one squad scooting forward to engage the Genestealers. One Priest + Libby are here. The squads on the right move out far enough to be on the objective in that area forcing me to come a ways out to engage him or not engage him at all.
The Devs all fire at a single Tervigon and manage to skimp off two wounds (close to the average of three wounds from 12 missiles with cover) and assaults the Genestealers with the ASM. They kill two and lose two in return.
This was a bad start for Jason personally. The Genestealers & Fexstars are his biggest threat and the opportunity to shoot at Tervigons before Catalyst is thrown up is nice but the Genestealers are what will chew through his army. Sending a single squad of frags at them would have made them a lot more manageable for his small ASM squads - as it was, not getting chewed to pieces in the first turn was a bit lucky for him as it would have given me free movement. By also putting his ASM in the centre, most of my firepower (i.e. Hive Guard) could still shoot whilst moving forward. He wasn't using his mobility to his advantage and was taking me head on.
Tyranids Turn 1
With Jason putting half his force right in front of me I can happily move forward - there's three objectives down the centre-line (width wise) and his army is there, good for me both. Dakkafexes move to get LoS to the models behind the central terrain piece with Hive Guard taking a back seat here as they don't care about LoS. The Termagants on left move up to engage the ASM in combat with the Genestealers to get a boost in movement whilst the Termagants on the right move up but don't fully extend - this way the ASM have to fully extend themselves and thus be in easy counter-assault range or leave me be this turn.
T-Fex holds centre - nothing really bothers him and no screen needed. Tervigons move up behind in spaces left open in army ensuring they have cover but I forget to spawn a backfield Termagant wrap. The combined fire of the T-Fex, Dakkafexes + Hive Guard drops a 5-man ASM squad with Priest and kills a couple more from the Libby squad. The Termagants join the Genestealers in assault but one Marine lives (Rends were stacked) and one Genestealer again bites the dust. Good for me as they are now locked in combat and cannot be shot.
Blood Angels Turn 2
The VV come in without needing DoA and drop in behind my army where I forgot to spawn a bubble-wrap. DoA ensures they land close to where they need to and eye off a Tervigon + Hive Guards. The ASM on the right move again to the extremes of my potential range to get to them but move one squad in to pull the Termagants towards them (forcing me to counter-attack and then be in range of his ASM next turn). I have more units than him though so I'd be happy to exchange units this way. The central ASM retreat whilst the Devs put more firepower on the Tervigon and drop two more wounds off it.
In combat the VV just assault the Tervigon and get some nice so wipe her out, consolidating into the ruins. In hindsight assaulting the Hive Guard here as well would have been a good idea! The ASM on the right assault the Termagants but leave three alive whilst suffering one dead of their own. The Genestealers finish off the lone ASM and consolidate towards the Devs on the left - the Termagants towards the central ASM.
Tyranids Turn 2
It's only my second turn and the centre of the table has almost been cleared of ASM already. My Hive Guard continue moving up into midfield with the remaining Tervigon who spawns a large number of Termagants and poops out. The Fexstar moves backwards to engage the VV whilst the other Dakkafex + T-Fex + new Termagants move over to save the other Termagants. The Genestealers move towards Devs and get a good Fleet roll whilst the central Termagants hang out in cover.
Shooting sees half the VV killed and the Hive Guard drop the final ASM + Libby squad in midfield. The MCs + new Termagants on the right clear out the ASM and consolidate backwards, again forcing ASM to come to them whilst the Genestealers engage the Devastators and stay locked in combat. The Fexstar drops the VV and moves back towards midfield with its consolidation move.
Blood Angels Turn 3
Only the ASM on the right flank left, soon to be only the Devs there as well. ASM on right setup multi-assault on both Termagant squads in an effort to start wiping out the remainder of my Troops. The position themselves so they are just engaging the Termagants when they assault and will pull the Termagants towards them. Nothing else can move so straight to shooting where the Missile Devs manage one more wound of the Tervigon (with Catalyst - down to two).
Assault commence and the ASM on the right charge and wipe out both Termagant squads with two squads consolidating back towards the Devs and one to block the T-Fex's movement. The Genestealers finish off the lone Devastator and consolidate towards Jason's objective.
Tyranids Turn 3
The T-Fex moves around the blocking ASM to drop as much damage on the final ASM squad. The solo Fex moves up to engage them in combat and consolidate closer to the enemy whilst the Fexstar also moves up. The Hive Guard hug the central terrain piece and work themselves within range of the Devastators with the Tervigon hiding from the Devs in the centre of the board. The remaining Termagants hunker down in terrain whilst the Genestealers move a paltry 4" (MTC + Fleet) towards Jason's objective.
Shooting sees the ASM squad brought down to three guys. The lone Fex assaults the blocking ASM, kills the Priest and sends the final ASM running but cannot catch him. He consolidates behind a tree to gain cover.
Blood Angels Turn 4
The lone ASM rallies and moves onto objective. The final three ASM move across to engage the final Termagants but one remains after assault. The Devastators start running away from my main force to try and preserve themselves and avoid a tabling.
Tyranids Turn 4
The Genestealers move up to help save the lone Termagant whilst the rest of the army moves + runs towards the fleeing Devastators. The Genestealers wipe out the ASM but not before they drop the lone Termagant and then consolidate onto Jason's objective. One Dev squad is half wiped out by firepower.
Both Armies Turn 5
The Devs keep running and I keep dropping firepower into them, wiping out one squad but not the Priest as he had switched squads. The Genestealers hold Jason's objective which gives me a full win as the game ends Turn 5.
Nearly a tabling and if the game had gone on, certainly would have happened unfortunately. Jason forgot my Genestealers were Troops and thus thought my Tervigon (having not moved to a side objective) wasn't holding an objective and the game was a draw. By splitting his army Turn 1 and not taking advantage of his mobility, I was able to walk pretty much across the field as I normally would like and use my durability and numbers to attrition him away. Assaulting the Genestealers rather than dropping several frags on them in the first turn also allowed them to be a threat the entire game and basically took on the left flank alone with shooting support.
I forgot to bubble-wrap my rear which allowed the VV to take out a Tervigon - this severely affected my ability to score and allowed Jason to try and wipe out my Troops and draw by default. Otherwise was a pretty straight forward game for me where management of charges was handled with Termagants.
Good game Jason and again, amusing argument at the end ^^.