Warden of the Inner Sky

As long as Warden of the Inner Sky has three or more counters on it, it has flying and vigilance.
Tap three untapped artifacts and/or creatures you control: Put a +1/+1 counter on Warden of the Inner Sky. Scry 1. Activate only as a sorcery.

Luminarch Aspirant

At the beginning of combat on your turn, put a +1/+1 counter on target creature you control.

Harbin, Vanguard Aviator

Flying
Whenever you attack with five or more Soldiers, creatures you control get +1/+1 and gain flying until end of turn.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Zephyr Sentinel

Flash
Flying
When Zephyr Sentinel enters, return up to one other target creature you control to its owner's hand. If it was a Soldier, put a +1/+1 counter on Zephyr Sentinel.

Champion of the Parish

Whenever another Human enters under your control, put a +1/+1 counter on Champion of the Parish.

Thalia's Lieutenant

When Thalia's Lieutenant enters, put a +1/+1 counter on each other Human you control.
Whenever another Human you control enters, put a +1/+1 counter on Thalia's Lieutenant.

Baird, Argivian Recruiter

At the beginning of your end step, if you control a creature with power greater than its base power, create a 1/1 white Soldier creature token.