Dubious Hags is a common raven unit that has above average strength at the cost of spawning a unit for your opponent. The strength of Dubious Hags can be increased when leveled up. Dubious Hags can fit into aggro decks well.
Dubious Hags' has high strength for its cost, but it comes with a downside. If Dubious Hags dies near your side of the board, the raven spawned can give your opponent a huge front boost.
Playing Dubious Hags so it has no empty bordering tiles can stop the enemy raven from spawning altogether, or use area damage to wipe it out.
You can also play Dubious Hags close to the enemy base, so that the raven spawned will clog up their available space.