Some basic cage theory:
Standard Cage
The above formation is a standard cage. It is where four players (X) occupy the corner squares of some fifth player, usually carrying the ball (B). Unless any of players X is adjacent to an standing opposing player, it is not possible to blitz the ball carrier without using special skills and / or making a really hard dodge roll (into three tackle zones). If any of players X are standing next to an opposing player, it is possible to push that player X away and blitz the ball carrier from the diagonal square previously occupied by X.
Players X usually have skills like Guard or Stand Firm to make it even harder to make a decent blitz on a ball carrier, and player B usually have skills like Sure Hands / Block to avoid loosing the ball on a -2 dice block.
Half cage
The above formation is a half cage, with the sideline (shown with |) covering two of the diagonal squares. The half cage requires considerably less players to set up compared to a normal cage, but it is also more risky. Do not use this tactic against teams with Frenzy, since they can easily push one of Player X into the crowd! Side Step is a good skills for players employing this formation, simply to avoid being pushed into the angry mob.
Breaking the cage
Ultimately, the goal is of course to hit the ball carrier. As mentioned above, this can be done by either pushing one of Players X out of position using a
Block action (and subsequently using the blitz on the ball carrier), or use special skills to bypass Players X. To set up for the push-away block, try getting at least four players into contact with two of the Players X, and simply hope that they will be unable to get rid of all of them. Note that this is a risky tactic for Skaven with their weak armour, and can easily leave you short handed! Graphically, this could look like:
Also make sure that as many players as possible are between the cage and your end-zone, to prevent the opposing team to form new cages and avoid your blocking screen.
Relying on special skills is probably a safer bet for Skaven, and the most obvious tactics are:
* Rat Ogre with Breat Tackle - Dodge into a full cage on 4+, and then get a two dice block on the ball carrier (make sure to mark players X to avoid assists, and also always plan ahead for the follow up block from Frenzy!)
* Gutter Runner with Strip Ball / Wrestle - Dodge into a full cage on 5+ with re-roll, and then get a -2 dice block on the ball carrier. If neither dice shows a Skull, the ball will be loose (but beware of Sure Hands to counter this tactic).
* Gutter Runner with Leap (Wrestle / Strip Ball). Same as above, but making a leap is easier than doing the dodge. A 3+ (or 2+ with Very Long Legs or AG5) takes you anyware you want to go. Make sure to have an apotecary near by, as roughly half of the opposing team will be able to smack the leaper in return!
An outsider is to use a Blitzer with Claw / Mighty Blow (/Piling On), and keep hitting Players X to get them of the field. Even though this might not stop the opposing team from scoring, you should be able to get rid of which ever player on the enemy team (apart from B) that is causing you the most trouble, and hopefully he will stay out for your upcoming drive.
Another way is to simply blitz away one of Players X, and try to put the Rat Ogre (or possibly a blitzer) in the tackle zone of the ball carrier. This won't get you the ball loose instantly, but it is a safer move and will force your opponent to either Block the Rat Ogre (and thus not moving forward), Blitzing the Rat Ogre (and thus not hitting any of your weaker players) or to risk a dodge from the Perhensile Tail.