Traditionally built classes start with one encounter power at level 1 and reach a maximum of 4 at level 11. Heroes of the Fallen Lands fighters start with one encounter power, “Power Strike”, and pick up multiple uses of that power until they reach 4 at level 13.
Power Strike: Free action.
Trigger: You hit an enemy with a melee basic attack using a weapon.
Effect: The target takes 1[W] extra damage from the triggering attack.
Level 17: 2[W] extra damage.
Level 27: 3[W] extra damage.
Power Strike lets you apply extra damage to a successful basic attack. The total damage from a Power Strike-enhanced basic attack is about equal to the damage from a regular encounter power.
Basically, while regular classes get 4 encounter powers, with varying extra effects, fighters get 4 copies of the same simple encounter power. It doesn’t have any extra effects, but it can’t miss either.
Having 4 power strikes is pretty fun, though they definitely are a bit underpowered compared to some other notable fighter encounter powers. This is mitigated somewhat by the fighter weapon specializations that add some nice effects when power strike is used. The coolest of these are probably the knight and slayer hammer and axe specializations, which immobilize and knock the target prone respectively.