Tactics for the Stronghold.

As I was recently explained, upgrading birds to level 112 can often be justified, firstly for dealing with difficult archers (snipers, for example), and also for quickly eliminating fast-moving units. Attacking Kent with birds and basic units on grassy terrain makes a big difference. But this is a tactic used when playing as Craig. If the hero is Gurnisson with a ballista, then there is less reason to do so.