Ava's stats are the worst in the game so far for a summoner, however, her ability Take to the Skies is without a doubt the strongest, giving flight to nearby commons is extremely powerful, the extra movement would be strong enough, and moving through units, friend or foe, is just tremendous value. The fact that it also allows movement through gates makes the movement potential almost unfair.
However, the faction relies a lot on Ava, and with only 10 life, just a single slip can put Ava in lethal range. Ava's power is very high but the faction is quite fragile with just one mistake forcing her to retreat or play an extra risky game. Abusing Ava and at the same time ensuring her safety is the balance one needs to maintain to be successful with Skyspear Avians.