Bosses are special units that are only used in single player. There are four types of boss: boss1, boss2, boss3 and boss4. Before a boss can be attacked, all regular armies on the territory occupied by the boss must be killed. When there is fog in the level, you can still see enemy tiles with boss1, boss2, boss4. When making single player level, you can give every slot up to 3 bosses. 
This boss is like a stack of 400 armies. This boss's armies will reduce when in combat (as offence and defence). Sametimes it deploys extra armies on territory where it is. It deploys every (1+5*k)th turn (6th, 11th, 16th) And the amount is: n= [(current turn-1)/5-1]*13+10. His 1st deploy is 10 armies, then 23 armies, 36 armies, 49, 62, 75, 88...
This type of boss has an increasing boss value and the boss must be fully killed in a single attack for the boss to be gone. This boss's value starts at 20. On turn 11, it's value will increase to 60 and on turn 14, the value will increase to 300.
This boss can only be killed in a single attack. This boss is originally worth 100 armies. Once a boss worth 100 is killed, it will spawn 4 lots of 90 army Boss3 (copy) bosses in random territories. Once a boss worth 90 is killed, a further 3 Boss3 bosses will be spawned with a value of 80 armies (copy's copy). These bosses can't be spawned on territories occupied by commanders.
This boss is a stack of 400 armies. This boss's armies will reduce when in combat (as offence and defence). It spawns even more armies. There are 2 types of spawns: 1) On any territory controled by ally team 2) On territory controled by enemy: it kills all armies in it, steals the territory and spawns armies there.
Armies start to be spawned in on turn 4 and every 3 turns after that. The amount of spawned armies is:
Starting with turn 4, and every +6 turn after that: 7*n where n's value is (remembering that it activates every 3 turns). eg at turn 22 n=7 (turns: 4,7,10,13,16,19,22) and the boss will spawn 49 troops.
Starting with turn7 and every +6 turn after that: 11*n. eg at turn 19 n=6 and the boss will spawn 66.
To make this clear, this is how many troops the spawn will create in the first 25 turns:
Starting with turn 25, both effects activate at the same turn and you will see 2 spawns. The boss is extremly dangerous and should be killed as soon as possible. It is possible to give this unit to slot, which will then not be assigned to any team (boss will be neutral). Neutral boss will add units on random enemy's terriotry and will steal your territories, turning them neutral and spawning troops there. Allied/ your boss will steal your territories, killing all armies in it in the process, give the territory to the player/ AI controlling the boss and add troops. It also adds troops to randomly selected enemy's territory.