Tyranids and cover

If you're new to playing (or fighting against) Tyranids the first thing you absolutely have to learn is that Nids live and die because of terrain.  Terrain rules are the single biggest contributor to a Tyranid win or a Tyranid loss.  The faster a player can learn to use terrain the better they will play nids (or play against nids).
The first and most beneficial aspect of terrain for Tyranids is cover.  Before you roll your eyes and say, "Gee thanks Captain obvious" here are a few facts.

• Only 2 models in the codex have an invulnerable save vrs shooting and they're both toughness 4.    
• Over 40% of the units in the codex won't get a save vrs a bolter.
• Over 70% won't get a save vrs a heavy bolter.
• Only 3 models in the codex will get a save vrs a Missile Launcher.

In a typical battle the Tyranid player will have about 3 rounds of movement before he can get into assault against a typical opponent.  In those 3 rounds you'll probably have to suffer 2 rounds of long range bolter shots and 1 round of rapid fire.  A good tournament player might delay the assault to round 4 if he's good but let's look at 3 rounds for argument's sake.  If one squad of Marines with 7 bolters, 1 bolt pistol, 1 plasmagun and 1 missile launcher focus fires on one brood of nids this is the damage they will do in those 3 rounds of shooting.

• Vrs Termagants and Hormagaunts the Marines will kill an average of 19 models.  If you're running broods of 20 the last Gaunt isn't going to do much in close combat.
• Vrs Genestealers the Marines will kill an average of 15 Genestealers.  If you're running broods of 12 then .... um.... you're dead.
• A toughness 6 monstrous creature will suffer an average of 5 wounds.  The 4 wound Carnifex never stood a chance.

Give them a cover save and the situation changes.

• The Gaunts now only loose between 9 and 10 models.  A brood that started with 20 can now do some good when they get there.
• The Genestealers now stand a chance to do something.  Their losses of 7 models still leave enough to have an effect.  
• The Fex now has 1 wound left.  It's not much but if it were a 6 wound Trygon it would still have a lot of fight left in it.

Now comes the bad effects of terrain on nids and it comes in 2 flavors.  The first and easiest to overcome is the slowing effect of cover.  It's difficult terrain and only models with wings, the Move Through Cover rule, or a Monstrous Creature will have a way around this effect.  Fortunately most of the models worth taking have one of these rules.  In fact of the models worth taking, only the Tyranid Warrior doesn't have a way around the slowing effects of cover.  Just keep that in mind if you have to charge through cover, you may not make it.  I've lost 1st place at tournaments because my nids came up 1 inch short on a charge attempt.  Trust me, it sucks.

The second way cover can work against a Tyranid player is our lack of assault grenade effects.  In my opinion this is the single biggest handicap in the codex.  Most Tyranids have a fairly good initiative statline.  Genestealers have a fantastic Initiative statline.  Without any assault grenade like effects that great initiative is reduced to a miserable 1.  

Guardsmen will swing before us, Orks will swing before us, everyone except friggin powerfists will swing before us.  Those 10 Gaunts and 5 Genestealers who survived all that shooting now have to survive close combat before finally getting their attacks and it ain't looking good for the hive.  Fleshhooks and Frag Spines do exist and they will provide the needed assault grenade like effect but none of those are troops or even worth taking.  

Tyranids are stuck pulling tricks to maintain our speed and initiative.  They can be tough to pull off and be point expensive but they're all we've got to work with.  I shall blog about them next week.