Abua Shi's ability is not as strong as many other summoner abilities, but what it is, is safe. You can very easily use it every turn, maybe at the cost of a more optimal move. From the safety of your side you can slowly use it for uninterruptible growth on your units. This is the reason this can be seen as mostly an economic deck.
Abua has a massive 5 ranged attack strength but not many ways to make use of it. However, often you can kill units at range without exposing him too much, which is a big part of the deck’s defensive plan.
Abua Shi needs to be close to his units, since most of his abilities and events have range requirements. Yet Abua has no tools to protect himself, which does present a challenge. Be careful with your gate placement, and don’t be afraid to have a unit acting as a bodyguard. The closer he gets to the center of the board, the more Abua can support his units' counterattacks, although he is also exposed to more danger the closer he gets to there. That tension is one of the main challenges of playing the deck well, especially against factions with high assassination potential.