In Battlejack, one might notice that most cards have three special attacks/ abilities. The first being a leader/ friend skill, the second being a personal ability/ attack (ie. griffon with obex invictum). The third attack/ ability is what is known as a combo attack. It is used in conjunction with with another hero and is usually much stronger (ie. flann and zere, together create the attack " Bloodlust", which does  x6.0 Fire attack healing 50% of the damage done). These combo attacks are very important to consider creating a team. Having all four card types (dark and light use the same card) is less important then having a strong lineup (especially factoring in friends). For example, if one were to have 5 good cards, knight Flann, Royal Griffin, Doctor Froglicker, Zere & knight Rain. You are entering an earth and dark temple. Who would one choose? Right off the bat, knight flann and Zere have a combo attack so they are an obvious choice (also earth is weak to fire). Royal griffin is a good choice to help counter dark (also, obex invictum is a shielding ability), therefore it joins the team as well. This leaves two heroes, a water dragon, and an earth healer. The choice should be made based on strength and battle power, however, if both heroes are similar (ie. lvl 32 3* and a lvl 35 3*) Doctor froglicker would be the better choice, as Rain's weakness is earth. As for choosing your friend, unless you can find another combo, a water hero would be recommended.

This is a rudimentary list (in order of significance) of how you should create your deck.

  1. Battle power

Battle power (listed in the top right of your "hero screen") shows how strong your heroes are, regardless of external factors (ie. character type or combos). Its calculated by factoring in each heroes stats (after runes). This number should be a very important determining factor in team building, because, well, there's strength in numbers... :)

2. Combos