First off, I want to be sure you understand this is Tyranid…horde…movement…tactics. These movement types don’t work as well for Ork or Guard or Marine horde. Orks, Guard, and Marines are all geared towards Assault, Shooting, or a combination of both with higher survivability respectively. None of these types of horde have the survival capacity of Tyranids. Tyranids especially can dole out FnP to the necessary units and also have a few ways of producing new units mid-game.
Tyranids don’t win games by killing, but rather, by surviving.
This movement style is not about swooping in with your few elitist units and getting those quick kills. It is about taking your large units and moving them with calculated care to maximize survival.
What I like to call the tendril movement Tyranid tactics assumes that you have 90+ models on the board. This movement in particular is most useful in objective games where the main scoring objective is not close to home and outflank is not an option.
This method produced great results specifically for me in 'Ard Boyz Round 1 Mission 2 this year where there were 5 objectives spread about the table. My opponent was heavily mechanized Leman Russ/Vendetta Spam. While the opponent had the major edge in a spearhead deployment and I was only able to destroy a single Vendetta and 8 guardsman whilst my army was decimated to scattered squads of termagants across the board…I was able to massacre my opponent and take every objective except his (though thoroughly contesting his) due to him not being able to effectively neutralize any of my units.
This can be used to escort your unit across the board and into assault…though I do not always believe this to be the smartest option…(as is the case when fighting Tau with cover save reducing markerlights)
In any case….let’s get on with the actual explanation and leave your questions for below…
This would be your deployment via pitched battle or spearhead...I am only showing a portion of the board here to keep the image simple.
The red dots are Termagants and I assume a 7 inch move for combined move through cover and run each turn. This may be shorter than the average move but I thought it best to cut myself short instead of assuming larger.
15 of 30 Termagants will be in cover at all times.
You still have half your unit in cover so you might as well start thinking about your future moves...
Think of the terrain to the left as a pivot point. Once you reach it...those models stay put and swing the rest of their brethren forward. They maintain a new position of cover so those in the back may move forward and out of hiding.
Now when I first started playing I would conga line my termagants from one piece of terrain to the next...but what you may eventually realize is the inefficiency of such moves. You will see how that would make EVERY model first move to the left and then back to the right.
The shortest path between two distances is a straight line.
So....the more of your unit that you can move in a straight line instead of back and forth...the less you are wasting movement as a whole...while...maintaining cover and therefore survivability.
Of course then you might wonder why not just conga line those 15 Gants straight to the far cover and be done with it?...
In my model, the unit does not lose casualties, however in actual game play you can never expect your unit to be at full strength the next turn...you grab the closest cover here as a safety net of sorts because the distance to the far cover is just a little too great to assume you can get there with a half neutered unit. In addition, the safety net terrain gives you something to fall back onto in case you roll complete garbage for movement and run rolls.
Finally as you see here we have covered nearly half the span of a board without losing cover. As we reach the far cover we may quickly move our rear models forward and leave behind whatever cover that is now unnecessary.
Another great thing about this situation is that you may run a unit up the right flank without touching terrain at all as you are providing cover with your tendril unit. This is especially good for those elitest killy units that your opponent most likely wanted to kill first anyways...now they may run unhindered by difficult terrain and push forward a new threat vector faster than otherwise possible.
Another question I can see coming up is what happens when the very end of the tendril gets assaulted and not all of your unit can get into assault?...Well if your unit has been whittled down then it probably didn't stand much chance in assault and the other models are usually not far enough to be out of assault. If your unit is at full strength...ha...I have yet to see an opponent besides Purifiers that can take down even half a squad of termagants in a turn...before the rest consolidate in. Also most enemies who are dangerous in assault have higher than I3 and so you simply remove those models further away before they even had their turn to fight back anyways.
As always, i heartily encourage conversation.