Quote: (markHargrave @ 13 Feb. 2009, 12:09 )
Can you shoot at the lander before it disembarks...
Nope. A transport can be intercepted in the air as Ginger points out. However, the unit has to complete a move to trigger OW. The approach as aircraft was deemed to not be a move for that purpose; only ground moves count. Disembarking triggers as normal, but obviously if they have disembarked you cannot catch the troops inside the transport.
Historically, the reason for this "ground move only" ruling was that IG Deathstrikes were the ultimate anti-air-assault defense. No LOS required; unlimited range. Drop them on OW and dare any air transport to come on board.
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Dav: I dread facing Vultures/Troopers with Orks - fast, good firepower and good FF make them a big threat for Orks.
As noted by others, Fightabommas will wreck Valkyries/Stormtroopers. At 450 points for 9, they can brave a lot of flak. Even if you assume 2 of them are shot down, that's 7 shots at AT4+. If the IG player keeps the Stormtroopers loaded, they will likely die with the Valks. If they unload them, then you add the FB's AP6 shots (AP5, but the Troopers will almost certainly be in cover). Either way, you're likely to get 3+ kills.
Past FBs, the options get pretty limited pretty quickly. If they are starting the game on OW, they must have been garrisoned, so you at least know where they will be. Since Orks have some decent garrisons of their own, you might be able to snag them by deploying so you can reach them.
One option is a cheap sacrificial formation. Throw a 220 point Stormboyz/2 Deth Kopta formation at them. You can keep most of the units outside of 30cm, and you only need to have 1-2 of the Valks in range, so only those in range can use OW. They can either blow their OW on a cheap formation (which can spread out quite far to minimize damage from barrages) or take the risk that a shot or two from the Deth Koptas will get lucky.
Another option is to hit them with a formation that can take the OW. A Warband with Stompas/Dread/Kanz can garrison and lay down decent firepower. If you can approach the Vultures in cover then they only hit on 5 for infantry and 6 for vehicles, and your infantry get cover saves. Depending on the kinds of walkers, you might still be able to keep most of the units outside 30cm to minimize OW ability. That 4-6BP barrage won't do a lot to slow down ~450 points of warband + walkers. The Warband probably won't do much damage to the Valks, either, but it burns the OW and keeps the Troopers from activating.
Another option is to have a couple Zzaps or Soopaguns. Since they can hit the Valks from well outside their OW range having just one or two Oddboyz will pretty much force the IG player to hide the Valks. That prevents the Orks from killing them outright, but it also severely hinders their forward deployment and OW ability to help you deal with them.