So I am not going to go into a lot of detail on deployment, each type of deployment has a 24" No Man's Land. As a Tyranid player your plan for deployment has to start at list building. You need to have a plan for getting into you opponent deployment. It can take the form of Flying Monstrous Creatures, Jump Infantry, Outflanking Deepstriking units, Fleet units Foot Slogging and running or combinations. Have a plan! I have certainly felt the effect of not crossing the battlefield fast enough, don't let it happen to you. Also remember if you're placing terrain using the alternating method, this is your first deployment phase. Use terrain to give yourself cover during deployment and while moving across the board and use terrain to block your opponents firelanes.
Missions
Mission Special Rules
Night Fighting
Really helps Tyranid players, especially if it goes off early in the game by giving us some better cover while we move into position to get at the enemy, really doesn’t hurt us since most of our weapons cannot shoot over 36 inches anyway.
Reserves,
The new mechanic of 3,3,auto is much more reliable than before, coupled with limiting the number of units that can be placed in reserve I think the overall mechanic helps Tyranid players. We really don’t have any good all reserve builds IMO (I would be happy to be proved wrong so GO FOR IT). IF you play against someone who uses a lot of reserves and you have been bubblewrapping important units to protect them its unlikely you will have to bubble wrap past turn 3.
Mysterious objectives.
This mechanic is in every book mission that has objectives. There is only really one that helps Tyranid players, Scatterfield, any bonus to cover saves is appreciated. Important to note here that while Sabotaged effects all units in range, the beneficial effect of objectives only effects the scoring unit with a model closest to the objective. Skyfire Nexus would be great for Tyranids but few of our scoring units would really benefit from this. Since most anti-tank is wrapped up in Elites and they cannot score in any of the missions so they cannot benefit from objectives.
Mysterious terrain.
If you play with it great, have at it, I don’t so I can’t speak to it. Interesting though that it is not listed as a special rule in any of the book missions. I am not saying they couldn’t be fun, I just have no experience with the game mechanic.
Secondary Objectives
Slay the Warlord
Pretty self explanatory. You kill his 1VP, he kills yours he gets 1VP. So know where his warlord is and protect yours when you can.
First Blood
The first unit that is destroyed gives up a VP. No matter how they were destroyed. If your opponent goes first and loses a unit on Deep Strike (destroyed) then you Get a VP. Since this is the only VP that both players cannot earn plan your early targets accordingly and protect you soft units accordingly. This Victory Condition can heavily favor the player who goes first.
Linebreaker.
At the end of the game have one of your scoring/denial units in you opponents Deployment Zone you get a VP, just one no matter units there are. Most units you will field as a Tyranid player will count for this(only spore mines, ripper swarms and skyslasher swarms don’t count) Not so true for your opponent. Vehicles themselves don’t count (except in Scouring and Big Guns Never Tire) and units embarked in vehicles don’t count.
Missions.
Crusade
This is a D3+2 mission where each objective is worth 3VP each to the player controlling it at the end of the game. So if you control more objectives than your opponent Secondary missions don’t matter as much they do however help to break VP ties.
Purge the Alien
Kill points, simple enough. This is the only true kill point mission in the Book missions. So if you play Tervigons spawn away unless it's this mission then think about it. In this one Secondary Objectives can matter a lot since both Slay the Warlord and Fist Blood are basically worth 2VPs each.
Big Guns Never Tire
Really the same as Crusade except that Heavy Support units can score, but be aware they also give up a VP if destroyed. Know which one of your opponents units are Heavy Support.
The Scouring
This one is kind of like Crusade except Fast Attack units also score and give up VPs is destroyed. This is also the mission with objectives that are worth Variable Values. One 4, two 3, two 2 and one 1. This is my least favorite book mission. I have only played it once and the 4 ended up being an objective in board center which was great, but I have seen games where one player has 4-3-3 in his deployment and his opponent got 2-2-1 in his. Didn’t really like seeing that.
The Emperors will
Not much to say here, with only two objectives of equal value the secondary objectives are very important in this mission.
The Relic
Commonly being call “40k Blood Bowel” around the internet. No objectives and a relic in board center. Secondary objectives can be very important in this mission as well. The relic is worth 3VP to the player controlling it at the end of the game. The relic is essentially a moveable objective. Only scoring units can pick it up (seize it) and the end of the movement phase if your unit moves into base to base with the relic you can pick it up. Important things to note. The relic can only move 6” at a time and a unit with the relic cannot run. You can move it from one model to another at the end of movement phase while being in BTB or from one unit to another. A unit with the relic can enter a vehicle but it still can only move 6" a phase. So if a unit with the relic can turbo boost they could move 6" during movement and 6" during shooting. Unfortunately there are no Tyranid units who can take advantage of this.
Overall I think things got a bit better for the tyranid player with regards to missions in this edtion. I have always felt that tyranids can do very well in objective based games. While flyers are/can be a big problem for Tyranid players, they cannot really score/deny objectives. Even in Big Guns Never Tire and The Scouring the could not easily get their hull within 3" of an objective to score/deny it. They can on those missions however contribute to linebreaker.