Celeste is a combat summoner, after all she is ultimately just health and strength. She needs units on the other side of the field to reach her potential but the whole faction is designed to achieve this, and remember that she herself counts as a unit on the other side for her own ability.
Celeste has a key role in the deck as the main source of damage. In general Wayfarers trade mobility and trickery for low damage potential so they rely on Celeste to do the heavy lifting for damage output. Her 6 strength potential is essential to tear down the high life units the opponent will use to try to slow down the advance and is a great amount of strength to destroy 5 life gates, which is one of the main ways Wayfarers apply pressure.
In addition to doing the heavy lifting when it comes to damage, the deck relies on her to threaten the opponent’s summoner. Her 6 strength will often be the way to assassinate, as two shots from Celeste means 12 dice, which can kill some summoners by itself. Thanks to their events Slip By, Astral Waypoint and Coordinate, it can be alarmingly easy to get Celeste in range of the opponent’s summoner. Boldo and Gem Dancers can also do great work to make it hard for the opponent to punish Celeste.
So you need to use Celeste a lot, and the opponent will try to poke her down to remove her as an option for you, be careful to only expose her when her 6 strength is really needed, otherwise let the work be done by her units as much as possible.