AS I understand it in a lot of Worlds there are no more than one level for any troops, some worlds may have 3 levels. There is no real health or weakness, you just lose troops.
Some troops are best for defense, sentries guardians (These are good for attack as well), Generally I try to use Lancers and Sentries mostly in defense, as the lancer in a attack for resources does not carry a lot of resources.
For attacking I use Knights and Berserkers. THe individual qualities of the troops are listed under the help icon in the game and the qualities of each are thoroughly explained.
Rams of course are good for destroying walls, and Ballistas for hitting anything you want. I go for the Rally point first as this prevents someone moving troops around. OF course if they have multiple cities or an effective Guild they could call for help and destroy you.
