"Army slots" are the bottom 3 slots in each build. They are awarded from successful dungeon completions and every leader has a distinct pool of options. Each slot can be changed after unlocking by spending Arclight Energy.
Summary
Jaina makes her own bling.
Leader Ability
Arcane Brilliance
Increases the Level of your by 3 while Jaina is in play.
Traits
Elemental
Frost
Ranged
One-Target
Possible Army Slots
Talents
Blink
Periodically teleport away from attackers.
Clearcasting
Spells cost 1 less Gold (but no less than 1) if played immediately after Jaina.
Flurry
Frostbolts burst on impact, Frosting enemies near the target.
Recommended Build