Might is an indicator of players' current combined attack and defense force strength.
Another indicator of players' status is Player Level .
Might gains from attack forces[]
Attack forces can be recruited from Barracks . Or bought by mirthril. Normally might chests give you T2 or T3 troops.
Might gains from defense forces[]
Another, faster, way to gain might is to hire defense forces from City Wall . Unlike attack forces, these forces do not consume food upkeep.
Until Wall Defenses get a nice revamp, they will more than likely lure people to attack you instead of providing any real defense. There are players that go through the World Map constantly looking for easy kills to increase their Troops Killed ranking. Since the Wall Defenses are easily killed, any player can send quite a small army to devastate a large Wall Defense.