Adding a tank or two to your army makes a big difference. As always, don’t over do it. Tanks that are not supported by friendly infantry are vulnerable to enemy infantry. Tank are most useful when there is less scenery, their weapons tend to be longer ranged and line of sight is needed.
Tanks often have several weapon choices. Sometimes this is the choice of the main weapon, often it is the choice of secondary weapons. This choice will have to be made at the time you build the tank. Think carefully when building your model, and think about ways to leave the weapon choice as flexible as possible. For example, can you fix the weapons on by Blutac, clips, or magnets so you can swap the weapons as needed?
Also while you are thinking about what weapons to add to your tank, have a think about where they are placed too. Some tanks can have the guns forward or further back. As the range of the weapons are measured from the guns themselves I highly recommend placing them as far forward as possible.
If you take a tank with several weapon remember that they all have to shoot at the same target. Decide if the tank will have a anti-tank or an anti-personnel role and equip accordingly. A tank with mixed weapons will be more flexible, but one set of weapons will be redundant each turn. If you are unsure take two tanks, one armed for each role.
5″ Blast Marker
Most Ordinance Weapons use the nice large 5 inch blast template. This makes nice large holes in swarm armies.
Move and Shooting Ordinance
You can move and shoot ordinance weapons with the usual penalties.
Ordinance Damage Table
When rolling for damage you get two dice and get to pick the highest. This means that you will get a vehicle destroyed (roll 5 or 6 ) on a glancing hit 20in36 times simplified to 5in9 chances. This means that for every nine attempts you will destroy the enemy five times. When you get a penetrating hit this increases to 24 in 36 chances simplified to 2 in 3 chances.
As Tanks are big and can block movement and line of sight, how you place your models can make a big difference in the outcome of the battle.
Tanks As Cover
Tanks block the line of sight. This means that if you hide your troops behind a tank they can not get shot (guess and template weapons, excepted). This is great if you want to do a ‘sneaking advance’, i.e. one of the slower armies (Imperial Guard, Salamanders, etc.) need to advance. The counter tactic to this is to use guess weapons that do not need a line of sight. Placed correctly the blast template would hit the weakest tank armour at the rear.
The down side of using tanks as cover is that they blocks the line of sight for your troops too. Also advancing tanks are susceptible to assault by Power-Fists and melta bomb welding maniacs.
Tank cause tank shock
This can be used to scatter your opponents formations just before your tactical squads assault. Yesterday I saw one player tank shock another Space Maine squad that was on the table edge. The squad failed it’s leadership test and ran clean off the table!
Transport Vehicle Tactics
When you are using transport vehicles, you should be asking yourself, ‘Why am I transporting these troops?’ and ‘Where do then need to go?’. If you realised that you do not need to move the troops, don’t bother with transporters and use the points for something else.
Common uses for transport Vehicles are for speeding up and protecting assault troops, rapid deployment reserves, ‘hit and run tactics’, and as bait for traps (see below).
Transport Vehicles can also be used as mobile bunkers as half the occupants can shoot from in side. Please note that if the Vehicle moves then the troops count as moving so they can not fire a heavy weapon.
Most Transport Vehicles have quite light armour as tanks go. Bolter’s can glance the Armour where the Armour Value is 10, and a Heavy Bolters and Heavy Flamers can cause glancing hits where the Armour Value is 11.
Blocking Line of Sight
All Vehicles block line of sight. This is great if you want to advance your troops forward. Move the Vehicle ahead of your troops and your opponent will have limited targets to shoot at.
Most Transport Vehicles can be armed with weapons. Imperial Guard and Marine transport can be upgraded to have a Plintle Mounted Storm Bolter too. These weapon upgrades are recommended as they give a use to your Transport Vehicle once your troops have been delivered.
Move your vehicle around to the back of an assault, or through a squad that you are about to assault. If you can cause tank shock along the way, you have the chance to catch that squad in cross fire and wipe then all out.
Keep your Transport Vehicle in the general area of it’s assigned troops so they can pop back in to it and cause mayhem else where as a moments notice.
Bait & Run
Troops with a Transport Vehicle make excellent bait for traps. If you make the target look vulnerable your opponent may well move forward to attack it. At this point you could either withdraw just enough for him to follow you and then counter attack from an unexpected quarter.
If you are playing tactical objectives tanks and transported troops can race in and grab objectives.
Since version 5 rules of Warhammer 40k, transport vehicles can pick-up and drop off other squads (if they can fit in). They can only carry one squad at a time, but it does mean that by investing points in one transporter, you can increase the effectiveness and value of several squads.