What is anti deployment? Anti deployment is starting with units in reserve. It used to be that each player would take turns deploying one unit at a time. Now one player first deploys their army then the other player deploys theirs. I have noticed a lot of players don't use the ability to hold units in reserve and I think they are missing out on a great tactic. I sometimes like to hold my best assault units in reserve and then bring them in. For the spearhead deployment your reserves can come in across the entire long table edge, not just your table quarter. This prevents the opponent from shooting them. This is a fantastic tactic for orks... Basically you take a strong unit such as Nobz with a warboss and put them in a trukk or battlewagon, don't forget the red paintjob. The turn they come in the transport moves 13" then the squad disembarks another 2". The warboss then calls down the Waaagh for a d6" fleet move and then they can charge up to 6 more inches. 13" + 2" + d6" + 6" = 21" + d6", or all the way up to 27" total. If it were me I'd always run Ghaz for this style army, you can't beat the guaranteed 6" fleet. Suddenly enemy units over halfway across the table are getting pounded by a huge power klaw. I think of this as an advanced anti-deployment tactic since I don't see many ork players using it. If the mission is objective based then place one of your objectives to lure in the opponent.
Using anti deployment has been with us a long time... Wolf Scouts, webway portals, terminators, drop pods and the monolith all come to mind. I personally think that drop pods were played out a long time ago but for some it's a brand new way of playing SM. I even used the old rules for drop podding prior to the release of the 4th edition SM codex... You had to go all drop pod though and there have always been some restrictions on what you can place in a drop pod. It was a great way to quickly close with the old static armies such as Iron Warriors. I have always been a big proponent of anti deployment and it only makes sense that I play daemons now as just like an old drop pod army everything starts in reserve. Deployment is meaningless to a daemon army and this is one of their biggest advantages.