Every hero in Last War: Survival belongs to one of three troop types - Tank, Missile Vehicle, or Aircraft - and the three form a clean rock-paper-scissors counter system: Aircraft beats Tank, Tank beats Missile Vehicle, and Missile Vehicle beats Aircraft. Each advantage is worth roughly 20% increased damage dealt and reduced damage taken, so the matchup is decided before raw Power even enters the calculation.
Tanks absorb damage and hold the frontline, protecting your backline while soaking up incoming fire. Missile Vehicles specialize in long-range, high burst damage. Aircraft bring speed and strong area damage, particularly against Tank-heavy lineups.
The single most important lesson for building a squad: commit to ONE troop type rather than splitting investment across all three. Formation bonuses, gear sets, research buffs, and Exclusive Weapons are all troop-type specific - a buff aimed at Tanks only helps Tank heroes, so splitting your spending across two or three types means every system you invest in delivers partial value instead of stacking toward a real advantage. Five heroes of the same type in one formation can be worth a large stacking bonus that a mixed lineup simply can't match.
Positioning also matters: your strongest hero generally goes in the first slot, since it's the first to engage in both attack and defense.