That is a great diagram, the only thing I'll add is that the Enemy unit cannot declare a charge against Unit 1 given the present setup, because he knows it will fail. You can never declare a charge that you know will fail. Now if there is another enemy unit nearby that is declaring a charge on Unit 2, or if the enemy will have some way of "clearing the path", then it becomes legal for the enemy unit shown to declare a charge against unit 1. This is because it is now uncertain that the charge will fail, because unit 2 might flee out of the way first, or be forced to rank up, both of which could make Unit 1 reachable by the Enemy unit shown. Given the position of the Terradons in the diagram though, the Enemy unit could declare a charge on the Terradons and the direction of their flee move will cause the Enemy to contact Unit 1 anyway (an incidental charge). If the closest Terradon were moved to the right a bit more it would change the angle of flight enough to solve this problem.
Well, I think this explains why I never have any luck with my Skirmisher redirects. We have been playing that you declare the charge with the unit. then if anything is in between that unit and its target then it ends up charging the unit in the way instead. I will have to reread the rules again (god, I read that damn BRB so many times and I somehow missed this???), but if that is the case then Terradons just became really useful, not to mention my Skirmishing Skinks! The hardest part will be convincing my group that we have been playing it wrong all this time (especially since the new interpretation is to my advantage!)
I think most of the skirmisher clarifications were in the BRB FAQs for 7th edition. I only recently gave those a good read through, but they certainly do make skirmishers more powerful!
Yes they still have a hit and run rule, but it is nowhere near as good as it was in 6th edition. Its just feigned flight now so they auto-rally if they choose to flee. In the old rules they could effectively leap in and out of combat on the turn they charge, which gave them a whole new role since they didn't have to worry about being stuck in combat. And if they did their hit and run, they couldn't be pursued as Barotok said.
oh... but i thought that terradons still had to rally. it says if a unit decides to flee and rallies they can reform and move.
You thought correctly. Feigned flight applies to a very specific situation... If the Terradons flee as a charge reaction AND subsequently pass a rally test, they are then free to move and shoot as normal in the same phase, instead of simply rallying and doing nothing that turn. Essentially it lets them be an ideal bait and flee unit. You just have to wonder if it is worth risking them in this manner.
The feigned flight rule relates to flying cavalry and fast cavalry rule sections in the main rule book. If you're not familiar with them it may be a great time to read up a bit on it. As far as using my expensive terradons as a bait and flee unit, I think this is just a little better choice than COC given their points cost. In the off chance they get caught (you roll a low flight roll), you're giving away an expensive unit. I would see myself only taking advantage of this rule if I was not expecting a charge and was forced to flee (IE I made a mistake deploying and moving them).
I could definitely see myself using this rule later in the game. Say you exposed your terradons to fire or had to charge them into an earlier combat, and for whatever reason they have fallen below half strength. Now it becomes a slightly less risky proposition, as you are only risking half of the unit's value at this point. Also, if they fall below US5 and have already dropped their rocks (by this point I'm sure they have), then charge baiting is probably the best thing to do with them. With the way skirmish units flee charges and the terradons ability to fly 20" to get in a perfect position, it shouldn't be tough to find a way to use them in this capacity. Just remember to always weigh the cost of doing vs. not doing it, especially near the end of the game. Also bear in mind that you shouldn't attempt this in turn 6 unless you are sacrificing them to save a more expensive unit (i.e. greater than half the remaining points of the terradon unit), since obviously you won't have a chance to rally them. Other instances to use the rule would be situational, but always keep in mind that the risk is not static. If the terradons would be able to fly through a friendly unit (hopefully one ItP or near the general) then you at least know they are even less likely to be caught. Also if the flee move will leave the terradons within range of the general (or the war drums), you can be fairly confident they will make their rally test.