Target spell -doesn't work?!

[Vulture]

The 'Target' spell does work properly. The answers to why these things happened are practically given by yourself.

a) Vampires are lvl 3 creatures (ancient ones are 4). If a unit is feared, as the spell description says, it won't attack units higher than them. In it's feared state, logically it won't obey to the 'Target' spell since the targetted vampires are higher in lvl.

b) archers that are blocked by a unit within melee range will step away if they can and most likely attack the unit they stepped away from. They rarely do otherwise but if they do, they ignore the 'Target' spell due to some glitch.

c) as already mentioned by iregev: enemy AI is low but not totally f'ed up. If an enemy melee unit can choose from a random target within range and a unit that is further away that it can't reach in ONE turn, they WILL ALWAYS go for the target in their range. Regardless of 'Target'. Make sure that your tanking unit is close enough to the enemy and the 'Target' spell will work properly.

Rest has been said already. Lvl 5 units won't be affected.

As long as you don't have good crowd control (dryads <3) multiple low level archer stacks are a real pain in the ass if you don't use 'Target' on a regular basis. Imagine 2 stacks of 'Catapult' and 4 Stacks of 'Scoffer Imp' acting freely on the battlefield. 'Target' makes them predictable and limits your loss-preserving actions ('Timeback', 'Ressurrect') down to one unit. In your case with vampires it's even double-win :>