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I tend to make alot of lists with tomb spyders to help with their WBB rolls is that a good idea or should i be spending the points else where thanks.
Tomb spyders are awsome for their points. The WBB coverage is certainly a bonus when you want to spread units out a bit further but I mainly use them as CC support. A cheap MC is always handy to have, particularly when it can protect itself from shooting with a scarab swarm. Great for phalanx support.
Necrons W68-D13-L10 (3rd edition codex)
Necrons W3-D1-L1 (latest codex)
Skaven still being assembled
Yes they are, I use em regularly! They are great for counter assault, being cheap and having the ability to inflict damage. Watch out for WS 5 guys, though, as you will be hitting on 5's and that makes for a sad spyder. Make a single swarm, as I'm sure you're aware and you have an ablative wound(s) for the inevitable heavy weapon blast coming their way. If you only have 1-2, keep em back with the warriors + such to help there, but if you have 3+, you can send em off together as an effective tank hunting unit. They can fan out a bit so they won't be so easy to go around and suddenly branch off if they want to gang up on a different vehicle and/or that troop squad that the enemy placed on his objective near his deployment. I'd recommend keeping them CCish.