Aurelia, Exemplar of Justice: Just a bomb card. It blocks well, boosts every other creature in this deck, mentors well, and can be mentored.
Boros Challenger: A 2/3 for 2 is solid and easily castable in this deck. It provides a mana sink and allows the ability to mentor more creatures in the late game.
Legion Warboss: A source of tokens that provide targets for mentoring.
Light of the Legion: If this survives, it will end the game quickly. Can mentor everything in the deck, and even it if dies, it can still provide value.
Skyknight Legionnaire: 2/2 flying and haste for 3 is a great fare and can quickly close out the game when it gets mentore once or twice.
Sunhome Stalwart: It has first strike, so it can survive early combat, and can mentor the goblin tokens.
Swiftblade Vindicator: This might start off as a 1/1, but it is the best mentor target available, and can become a must answer threat quickly.
Tajic, Legion's Edge: A hasty 3 power creature that can mentor quite a few creatures and act as a lightning rod for opposing damage based removal.
Truefire Captain: This can mentor just about any creature in this deck. It discourages damage based removal, and blocks.