Here's a list of all Uncommon Champions:

Tariq / Engineer
  • Battalion slot: Siege Machines
  • Passive: Increases Battering Ram damage
  • Active: Reduces nearby battalion damage
Matilda / Engineer
  • Battalion slot: Siege Machines
  • Passive: Increases Catapult damage
  • Active: Deals damage and reduces the speed and defense of units around the current target
Lance / Engineer
  • Battalion slot: Siege Machines
  • Passive: Increases Trebuchet damage
  • Active: Deals damage and reduces the defense of units around the current target
Halina / Miner
  • Battalion slot: Infantry / Ranged / Mounted
  • Passive I: Increases Mining Capacity
  • Passive II: Increases Mining Rate
Thomas / Miner
  • Battalion slot: Infantry / Ranged / Mounted
  • Passive I: Increases Load Protection
  • Passive II: Increases Mining Rate
Rowan / Officer
  • Battalion slot: Ranged
  • Passive: Increases Archer damage
  • Active: Increases the attack of nearby friendlies and decreases the target's defense
Erik / Officer
  • Battalion slot: Infantry / Ranged / Mounted
  • Passive: Increases Axemen damage
  • Active: Deals splash damage and reduces the target's attack
Liona / Officer
  • Battalion slot: Mounted
  • Passive: Increases Cavalry damage
  • Active: Increases your battalion's speed and defense
Valentina / Officer
  • Battalion slot: Mounted
  • Passive: Increases Lancer damage
  • Active: Deals damage over time to current target
Gerard / Officer
  • Battalion slot: Infantry / Ranged / Mounted
  • Passive: Increases Swordsmen damage
  • Active: Increases battalion's defense for a bit and taunts nearby enemies
Cassian / Officer
  • Battalion slot: Ranged
  • Passive: Increases Crossbowmen damage
  • Active: Damages the current target and causes nearby friendly units to attack it